Indonesia says it will build a new warning system capable of detecting tsunamis caused by undersea landslides, days after giant waves triggered by a volcano killed at least 429 people. Installation of the new structure of buoys would start next year. It is thought that activity by the Anak Krakatau volcano set off undersea landslides, causing this week's tsunami.

Officials say some 150 people are still missing and 16,000 have been displaced. Rescue workers, helped by heavy lifting equipment, are going from village to village, sifting through the debris looking for survivors in badly hit areas on the islands of Sumatra and Java. The new mechanism would work by detecting the size of waves, Iyan Turyana, a spokesman for the Agency for the Assessment and Application of Technology, told the BBC's Indonesian service.

The existing technology failed to predict the tsunami that devastated coastal towns around the Sunda Strait, between the islands of Sumatra and Java. The system has been set up to monitor earthquakes, but not undersea landslides and volcanic eruptions, which can also generate deadly waves.

Japanese stocks plunged and other Asian markets declined following heavy Wall Street losses triggered by President Donald Trump's attack on the U.S. central bank. The Nikkei 225 fell by an unusually wide margin of 5.1 percent to 19,147.45 points. The Shanghai Composite Index lost 2.1 percent to 2,473.75. Benchmarks in Thailand and Taiwan also declined. Markets in Hong Kong, Australia and South Korea were closed for Christmas.

Wall Street indexes fell more than 2 percent after Trump said on Twitter the Federal Reserve was the U.S. economy's "only problem." Efforts by Treasury Secretary Steven Mnuchin to calm investor fears only seemed to make matters worse. U.S. stocks are track for their worst December since 1931 during the Great Depression. The market has been roiled by concerns about a slowing global economy, the trade dispute with China and another interest rate increase by the Fed.

Thailand's parliament has voted to approve cannabis for medical use, with a key lawmaker calling it a "New Year's gift" to the Thai people. Recreational use will remain illegal. Marijuana was used in Thailand as a traditional medicine, until it was banned in the 1930s. South East Asia has some of the world's toughest penalties for drug usage or possession, and Thailand is the first in the region to allow medicinal marijuana. Thailand's junta-appointed parliament voted to amend the Narcotic Act of 1979. It happened after an extra parliamentary session was arranged to push bills through before the New Year's holidays. The amendment will become law when it is published in the government gazette, The Bangkok Post reported.

"This is a New Year's gift from the National Legislative Assembly to the government and the Thai people," said Somchai Sawangkarn, chairman of the drafting committee, during the televised session.

A British-Iranian academic who was arrested and detained in Iran on security charges has returned to the UK, the Foreign Office confirmed. Prof Abbas Edalat, who works at Imperial College London, was detained in Tehran in April. The Campaign Against Sanctions and Military Intervention in Iran said he was released last week. British-Iranian charity worker Nazanin Zaghari-Ratcliffe remains in prison in Iran, where she has been since 2016.

Prof Edalat - who specialises in computer science and mathematics - was reportedly attending an academic workshop in Iran on 15 April when he was detained. At the time of his arrest, an Iranian news agency reported that Prof Edalat was part of a "network" of British spies whose members had been identified and arrested. Prof Edalat founded anti-war protest group CASMII, which opposes sanctions in Iran. The group said: "It increasingly appears, as we had suspected, that his detention in spring in Iran was a case of misinformation and misunderstanding by the Iranian security apparatus."