Washington, Nov 24 (IANS): The US issued a worldwide travel alert, warning its citizens of "increased terrorist threats" after the Paris attacks.

"Current information suggests that the Islamic State (IS), Al-Qaeda, Boko Haram and other terrorist groups continue to plan terrorist attacks in multiple regions," Xinhua quoted a state department post as saying on its website.

Possible attacks "may employ a wide variety of tactics, using conventional and non-conventional weapons," the post added.

"US citizens should exercise vigilance when in public places or using transportation," it said.

"Be aware of immediate surroundings and avoid crowded places, and especially be alert during holiday times," it said.

The travel alert will expire on February 24, 2016, it said.

The Islamic State (IS), a militant group that has overrun vast swathes of territory in Iraq and Syria, claimed responsibility for the bloody Paris carnage on November 13 that killed at least 129 people and injured over 350 others.

IS militants threatened to bomb the White House and launch more attacks in Paris, according to a recent video.

However, FBI Director James Comey last week said that these videos are just a kind of propaganda, "not credible intelligence".