LONDON (Reuters) - Intelligence agencies have disrupted plans for multiple attacks on European cities by a group thought to be linked to al Qaeda, Britain's Sky News said on Tuesday.
Militants based in Pakistan were planning simultaneous strikes in London, as well as cities in France and Germany, the channel's foreign affairs editor, Tim Marshall, said.
Asked about the Sky News report, U.S. security officials said they could not confirm that a plot had been disrupted. But they said they believed that the threat of a plot or plots was continuing.
U.S. counter-terrorism agencies are poring over intelligence reports suggesting a major attack plot is currently in the works against unspecified targets in Western Europe or possibly the United States, they said.
Four U.S. security officials, who asked for anonymity when discussing sensitive information, said that initial intelligence reports about the threat first surfaced roughly two weeks ago, around the time of the anniversary of the September 11, 2001, attacks on the United States.
Sky News' Marshall said an increase in drone attacks in Pakistan in the past few weeks was linked to attempts by Western powers to disrupt the plot, which was at an "advanced but not imminent stage."
British security sources declined to comment on the Sky News report.
Britain in January raised its international terrorism threat level to "severe" -- the second highest level of alert in the five-tier system.
The head of Britain's MI5 Security Service, Jonathan Evans, said on September 16 there remained "a serious risk of a lethal attack taking place."
EIFFEL TOWER ALERT
The Eiffel Tower and the surrounding Champ de Mars park were briefly evacuated on Tuesday because of a bomb alert, the fourth such alert in the Paris region in as many weeks, but a search turned up nothing, police said.
French Interior Minister Brice Hortefeux said on September 20 France faced a real terrorism threat due to a backlash from al Qaeda militants in North Africa, with fears growing of an attack from home-grown cells within French borders.
Citing unidentified intelligence sources, Sky said the planned attacks would have been similar to the commando-style raids carried out in Mumbai by Pakistan-based gunmen in 2008.
The heavily armed militants launched an assault on various targets in Mumbai, including the Taj Mahal hotel and the city's main train station.
The United States appeared to have widened drone aircraft attacks against al Qaeda-linked militants in Pakistan and might have killed a senior leader of the group, Pakistani and U.S. officials said on Tuesday.
U.S. officials declined to comment on specific plots in Europe or elsewhere but acknowledged that targeted drone strikes in Pakistan were meant to disrupt militant networks planning attacks.
"It shouldn't surprise anyone that links between plots and those who are orchestrating them lead to decisive American action," a U.S. official told Reuters.
"The terrorists who are involved are, as everyone should expect, going to be targets. That's the whole point of all of this."
The U.S. national security officials said that most of the threat reporting suggested that the targets of whatever plots were under way were in Europe. One of the officials said, however, that there was particular concern that U.S. interests in Europe might be targeted.
Two officials also said that they could not rule out the possibility that some of the threat reporting could relate to attack plots under way which might be directed at targets inside the United States. One of these officials added that the intelligence reporting was tangled and could mean that more than one plot has been set in motion.
U.S. intelligence chief James Clapper declined to comment directly on any European plot but stressed that al Qaeda remained committed to attacking Europe and the United States.
"We are not going to comment on specific intelligence, as doing so threatens to undermine intelligence operations that are critical to protecting the U.S. and our allies," Clapper, the director of national intelligence, said in a statement.
(Reporting by Karolina Tagaris, Estelle Shirbon and William Maclean in London, and Philip Stewart and Mark Hosenball in Washington; editing by Andrew Dobbie and Frances Kerry.)