Washington, Jan 5 (DPA) The unstable situation in Yemen poses a threat to regional and global security, US Secretary of State Hillary Rodham Clinton said Monday.

International efforts to support the Yemeni government in confronting extremism must be strengthened to prevent Al Qaeda from using the country "as a base for terrorist attacks far beyond the region," Clinton said.

"The instability in Yemen is a threat to regional stability and even global stability," she said after meeting with the prime minister of Qatar, Hamad Bin Jassim Jabr al-Thani.

US officials have long been concerned about the growing presence of al-Qaeda in remote areas of Yemen, and their apprehensions were highlighted in the failed Christmas Day plot against a US airliner.

The Nigerian suspect, 23-year-old Umar Farouk Abdulmutallab, reportedly told authorities he received training from Al Qaeda in Yemen and the explosives materials that failed to detonate on the flight bound for Detroit.

The US embassy in the Yemeni capital Sana'a was closed for a second day on Monday because of al-Qaeda threats against American interests. Clinton said the environment is under continuous review and the embassy will reopen "when security conditions permit."

The British and Japanese embassies in Sana'a were also closed.

Clinton said the State Department complied with its responsibilities in the inter-government process for handling information about potential terrorists or terror attacks, but it was reviewing the procedures.

"We are not satisfied," she said.