WASHINGTON, Oct 2 (Reuters) - The United States is considering formally alerting Americans to be vigilant as they travel in Europe in light of intelligence pointing to threatened attacks by al Qaeda militants, a U.S. official said on Saturday.

A plot to stage coordinated attacks in Europe was disrupted in its early stages by drone strikes against militants in Pakistan, but it was not clear if the threat was fully erased, security sources said earlier in the week.

The U.S. official, speaking on condition of anonymity because of the sensitivity of the issue, said the United States "is considering issuing a travel alert asking Americans to be vigilant as they travel in Europe given the most recent al Qaeda threat."

The official said the United States was consulting with European governments about the possible action.

There was no immediate indication when the alert might be issued.

A State Department official, speaking on condition of anonymity, declined to confirm the department would issue the alert, but said the United States remained attentive to threats posed by al Qaeda.

"We have been and continue to be focused on al Qaeda's interest in attacking us, our allies, and U.S. interests abroad. We will spare no effort to thwart terrorist plans and will take further actions as appropriate," the State Department official said, without elaborating.

Germany said it knew of information pointing to possible al Qaeda attacks in Europe and the United States, and intelligence sources said security agencies had disrupted plans by Pakistan-based militants for simultaneous strikes in London, as well as in major cities in France and Germany. [ID:nSGE68S066]

The plot involving al Qaeda and allied militants was in the early stages and would have involved groups of assailants taking and killing hostages, possibly along the lines of the 2008 raid in the Indian city of Mumbai in which 166 people died, the sources said.

Intelligence sources said an increase in strikes by unmanned U.S. drone aircraft on suspected militants in Pakistan in the past few weeks was part of Western efforts to thwart the plot. (Additional reporting by Ayesha Rascoe; Editing by Will Dunham)