As Bangladesh accelerates efforts to evacuate its distressed nationals stranded in war-torn Ukraine, families here are scrambling to get in touch with their loved ones.

"For God's sake, stop the war. I want my brother to come back home," Avishek Chowdhury, a civil engineering student from Chattogram, said about his brother Rohan Chowdhury, a medical student at the Kharkiv Institute of Medicine and Biomedical Sciences located in Kharkiv, Ukraine's second city where Russian soldiers entered Sunday.

In the fog of war, Ukraine's capital Kyiv was eerily quiet after huge explosions lit up the morning sky and authorities reported blasts at one of the airports.

As a strict 39-hour curfew kept people off the streets, only an occasional car appeared on a deserted main boulevard.

There have been major attacks in Kyiv that have created greater fear and panic among the population.

Terrified residents hunkered down in homes, underground garages and subway stations in anticipation of a full-scale Russian assault.

During the dramatic escalation of East-West tensions over Russia's invasion of Ukraine, over 400 Bangladeshis have so far safely crossed the Ukrainian border and reached its neighbouring countries, including Poland.

Forty-six Bangladeshis are in temporary shelters arranged by the Bangladesh Embassy in Warsaw. The rest of them made their arrangements although they were offered shelter by the embassy, says the government.

However, Bangladesh's Mir Hassan Naim said: "I came to the Poland border from Lviv, but it was a long and rigorous journey mainly because of the distance. To reach Poland, people from Kyiv have to come to Lviv or any other border town first. It is not too easy."

The Bangladesh Embassy in Warsaw is working to rescue and relocate 28 Bangladesh nationals as of now through the International Committee of the Red Cross, Ukraine.

It is also working to evacuate Bangladeshis who are in jail or detained in Ukraine through the International Organization for Migration, Ukraine.

Meanwhile, around 15 Bangladeshi students have arrived in Hungary and are now being looked after by the Bangladesh Embassy in Vienna.

So far, three Bangladeshis have entered Romania and are now being taken care of by the Bangladesh Embassy in Bucharest. Seven more are expected to enter Romania soon, said the Ministry of Foreign Affairs (MoFA).

The number is likely to go up in the next few days, said the ministry, as these Bangladesh nationals want to return home now.

"We are in touch with about 700 Bangladesh citizens," said State Minister for Foreign Affairs Md Shahriar Alam Saturday night.

The government's efforts are going on to help Bangladesh nationals get into Poland, Romania, Slovakia, Hungary and Moldova, all bordering Ukraine, said officials.

A team from the Embassy of Bangladesh in Warsaw is working near the over 500km-long Poland-Ukraine border to assist Bangladeshis wishing to enter Poland.

Amid the worrying development in Ukraine, a Bangladeshi ship has got stuck at the Port of Olvia, located in the Mykolaiv region on the left bank of the Dnipro-Bug estuary on the northern Black Sea coast. All 29 crew on-board are Bangladeshis.

Ukrainian authorities have reported fighting near Mykolaiv, Odessa, and other areas.

The bulk carrier Banglar Samriddhi, anchored at the port before the Russian invasion began on February 24, Omar Faruque Tuhin, a crew member of the ship, told UNB over the phone Sunday.

"All activities at the port came to a screeching halt immediately and we got stuck on the ship. Panic has gripped us. We hear the sound of explosions and gunfire in the distance. Fortunately, the port has not yet come under direct attack," said Omar.

"However, it is dangerous for our ship to move around as there can be planted mines in the sea," he added.

Russian forces had blocked the cities of Kherson on the Black Sea and the port of Berdyansk on the Azov Sea, Russian Defense Ministry spokesman Major General Igor Konashenkov said.

The pressure on strategic ports in the south of Ukraine appeared aimed at seizing control of the country's coastline stretching from the border with Romania in the west to the border with Russia in the east.

Cutting Ukraine's access to its seaports would deal a major blow to the country's economy.

It also could allow Moscow to build a land corridor to Crimea, which Moscow annexed in 2014 and until now was connected to Russia by a 19-kilometre bridge, the longest bridge in Europe which opened in 2018.

Earlier, Bangladesh asked its nationals stranded in Ukraine to contact the country's diplomatic missions in the neighbouring European countries while Poland and Romania came forward to provide temporary shelters for Bangladeshis.

The government will arrange chartered flights to bring back Bangladeshis from Poland.

The country will allow Bangladeshis to stay for 15 days upon their arrival from Ukraine and the government of Bangladesh hopes to bring back its citizens much ahead of the 15-day timeline.

Friday, MoFA issued helpline numbers for the stranded Bangladeshi nationals to help them get into Poland, Romania, Slovakia, Hungary and Moldova, all bordering Ukraine.

For Slovakia and Hungary, Bangladesh nationals were asked to get in touch with the Bangladesh Embassy in Austria.

Bangladesh citizens carrying passports can secure a travel pass at the border to enter Poland without a visa, but they need to carry two colour passport-sized photos, the Bangladesh Embassy in Warsaw said.

Bangladesh does not have an embassy or a consulate in Ukraine. The country's Embassy in Poland only acts as Ukraine's de-facto diplomatic mission.

Sunday, the UN refugee agency (UNHCR) said around 368,000 Ukrainians arrived in neighbouring countries since the invasion started Thursday.

The UN has estimated the conflict could produce as many as 4 million refugees, depending on how long it continues.

Until Sunday, Russia's troops had remained on the outskirts of Kharkiv, a city of 1.4 million about 20 kilometres south of the border with Russia, while other forces rolled past to press the offensive deeper into Ukraine.

President Vladimir Putin has not disclosed his ultimate plans, but western officials believe he is determined to overthrow Ukraine's government and replace it with a regime of his own, redrawing the map of Europe and reviving Moscow's Cold War-era influence.

Meanwhile, Ukrainians have volunteered en masse to help defend Kyiv, and other cities, taking guns distributed by authorities and preparing firebombs to fight Russian forces.

The number of casualties so far from Europe's largest land conflict since World War II remains unclear.

Ukraine's health minister reported Saturday that 198 people, including three children, had been killed and more than 1,000 others wounded. It was unclear whether those figures included both military and civilian casualties.

Russia has not released any casualty information.