WASHINGTON

Amid online “chatter” about terror threats, U.S. diplomatic posts in 19 cities in the Muslim world will be closed at least through the end of this week, the State Department said.

Spokeswoman Jen Psaki said the decision to keep the embassies and consulates shuttered is a sign of an “abundance of caution” and is “not an indication of a new threat.”

Lawmakers, though, said the intercepted chatter suggested that a major terrorist attack was in the planning stages. One lawmaker said the chatter was specific as to certain dates and the scope of the operation.

Psaki said the continued closures are “merely an indication of our commitment to exercise caution and take appropriate steps to protect our employees, including local employees, and visitors to our facilities.”

Diplomatic facilities will remain closed in Egypt, Jordan, Libya, Yemen, Saudi Arabia and Kuwait, among other countries, through Saturday, Aug. 10. The State Department announcement Sunday added closures of four African sites, in Madagascar, Burundi, Rwanda and Mauritius.

The U.S. has also decided to reopen some posts today, including those in Kabul, Afghanistan, and Baghdad.

The Obama administration announced Friday that the posts would be closed over the weekend and the State Department announced a global travel alert, warning that al-Qaida or its allies might target either U.S. government or private American interests.

The intercepted intelligence foreshadowing an attack on U.S. or Western interests is evidence of one of the gravest threats to the United States since 9/11, according to several lawmakers who made the rounds on the Sunday talk shows.

“This is the most serious threat that I’ve seen in the last several years,” Sen. Saxby Chambliss of Georgia told NBC’s “Meet the Press Sunday. “Chatter means conversation among terrorists about the planning that’s going on — very reminiscent of what we saw pre-9/11.”

Chambliss, the top Republican on the Senate Intelligence Committee, said it was that chatter that prompted the Obama administration to order the Sunday closure of 22 embassies and consulates and issue the travel warning.

Rep. C.A. Dutch Ruppersberger of Maryland, the top Democrat on the House Intelligence Committee, told ABC’s “This Week” that the threat intercepted from “high-level people in al-Qaida in the Arabian Peninsula” was about a “major attack.”

Yemen is home to al- Qaida’s most dangerous affiliate, blamed for several notable terrorist plots on the United States. They include the foiled Christmas Day 2009 effort to bomb an airliner over Detroit and the explosives laden parcels intercepted the following year aboard cargo flights.

Rep. Peter King, the New York Republican who leads the House Homeland Security subcommittee on counterterrorism and intelligence, told ABC that the threat “was specific as to how enormous it was going to be and also that certain dates were given.”

The Obama administration’s decision to close the embassies and the lawmakers’ general discussion about the threats and the related intelligence discoveries come at a sensitive time as the government tries to defend recently disclosed surveillance programs that have stirred deep privacy concerns and raised the potential of the first serious retrenchment in terrorism-fighting efforts since Sept. 11.