Eighteen of the 19 U.S. embassies and consulates that were closed in the Middle East and Africa because of a terrorist threat will reopen on Sunday or Monday, the State Department said Friday.

The U.S. Embassy in Sanaa, Yemen, will remain closed. The U.S. Consulate in Lahore, Pakistan, which was closed Thursday because of what officials say was a separate credible threat, also was not scheduled to reopen.

In the statement, U.S. State Department spokeswoman Jen Psaki did not cite a reason for the decision to reopen the 18 missions. She cited "ongoing concerns about a threat stream indicating the potential for terrorist attacks emanating from al-Qaeda in the Arabian Peninsula" for keeping the embassy in Sanaa closed.

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

The 19 outposts were closed to the public beginning last Sunday. Most American employees at the U.S. Embassy in Yemen were ordered to leave the country on Tuesday because of threat information.

Avoid all travel to Yemen, Canadians told

Canada has recently issued a travel advisory urging people to avoid all travel to Yemen.

"The level of risk to foreigners is very high as the security situation has deteriorated significantly," the statement says.

In an interview with CBC's Evan Solomon recorded before news of the embassy reopenings was released, Canada's Foreign Affairs Minister John Baird said that "we should all be concerned" when the U.S. takes the "significant action" of closing a large number of embassies in a certain region.

"We should all take that very, very seriously," he said.

Baird said that Canada has professional intelligence officers and foreign service workers who provide good advice as to "when and where and what action we should take in response to the specific intelligence reports that we get, and obviously we rely heavily on their experience and their expertise."

Canada closed its high commission in Bangladesh amid the threats.

An intercepted message between al-Qaeda officials about plans for a major terror attack triggered the 19 closures.

The U.S. State Department issued a travel warning Thursday night regarding Pakistan, saying the presence of several foreign and indigenous terrorist groups posed a potential danger to U.S. citizens throughout the country. At the same time, officials ordered non-essential government personnel to leave the U.S. Consulate in Lahore.