WASHINGTON - The United States on Friday issued a global travel alert over possible terrorist attacks, one day after it announced the closure of some diplomatic missions in the Middle East region over the coming weekend.

"The Department of State alerts US citizens to the continued potential for terrorist attacks, particularly in the Middle East and North Africa, and possibly occurring in or emanating from the Arabian Peninsula," the department said in a travel alert posted on its website.

"Current information suggests that al-Qaida and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August," it added.

US Ambassador to Libya Christopher Stevens and three other Americans were killed when the US consulate in Benghazi of Libya came under attack on September 11, 2012.

The State Department warned of possible terrorist attacks on public transportation systems and other tourist infrastructure, adding that the United States is working closely with other nations on the threat.

US missions in Egypt, Iraq, Israel, Kuwait and Saudi Arabia are among those to be closed through the weekend, in particular on Sunday, a workday in the Muslim world.

State Department spokeswoman Marie Harf told reporters on Thursday that the decision was taken "out of an abundance of caution and care for our employees and others who may be visiting our installations."

Cooperation on counterterrorism was the focus of the talks between US President Barack Obama and his Yemeni counterpart Abdal-Rab Mansur Al-Hadi at the White House on Thursday, as the Obama administration is helping the Yemeni government forces fight Al-Qaida in the Arabian Peninsula, a resurgent al-Qaida offshoot based in Yemen.