Authorities in Bangladesh today stepped up security for Western missions in Dhaka following a threat to blow up the US embassy and three other missions by a militant organisation, dpa reported. The US embassy and British, Australian and Canadian high commissions had received threats in a faxed message from Malaysia, an act claimed by Jemaah Islamiyah al-Qaeda, said AKM Shahidul Haque, head of Dhaka Metropolitan Police (DMP). Police vigilance in Dhaka's Gulsahn and Baridhara diplomatic enclaves was scaled up after the missions reported receiving the faxed threat Thursday night. Two hundred more policemen were deployed on top of the regular 600 used in the sensitive areas. Haque said the Jemaah Islamiyah, believed to have links with the al-Qaeda core group of Osama bin Laden, had warned Western diplomats "to shut their activities and leave the country within seven days". Shahidul said the group also demanded 100,000 dollars from the missions through Western Union Money Transfer to fund the release of a forensic expert of the group, who is now in a Malaysian prison.