WASHINGTON - The United States will reopen on Sunday 18 of the 19 embassies and consulates shut in anticipation of terror attacks, the State Department said on Friday.

The US embassy in the Yemeni capital of Sanaa will remain closed "because of ongoing concerns about a threat stream indicating the potential for terrorist attacks emanating from Al-Qaida in the Arabian Peninsula," spokeswoman Jen Psaki said in a statement.

The State Department ordered the closure of 22 diplomatic missions on Aug 4, a workday in the Arab world, to cope with potential terrorist threat based on intercepted communications purported to be between al-Qaida leader Ayman Zawahri and Nasser Wuhayshi, head of the Yemen-based Al-Qaida in the Arabian Peninsula.

It extended the closure of 19 diplomatic missions in the Middle East and Africa until this Saturday.

In addition, Washington evacuated non-emergency staff from its Sanna embassy and consulate general in Pakistan's Lahore respectively on Tuesday and Thursday.

Psaki said the consulate in Lahore will remained closed as well following its closure on Thursday.

"We will continue to evaluate the threats to Sanaa and Lahore and make subsequent decisions about the re-opening of those facilities based on that information," she said.

"We will also continue to evaluate information about these and all of our posts and to take appropriate steps to best protect the safety of our personnel, American citizens traveling overseas, and visitors to our facilities," she added.