US warning of commando terror attacks in Europe irritates European officials, who say no evidence plot is imminent

Fresh warnings of possible terror attacks in Europe issued by the US were not sparked any new intelligence, counter-terrorism, security and intelligence officials said.

There seems no doubt there has been "chatter", or intercepted communications, between suspected jihadists and al-Qaida sympathisers plotting in the tribal areas of Pakistan bordering Afghanistan.

The suggestion, first reported in the US press, was that they were planning a series of "commando-style" attacks, something European security agencies have feared since the co-ordinated killings in Mumbai two years ago in which 174 people died.

Attacks by gunmen, which could continue for some time, could provoke more terror than split-second suicide bomb attacks, officials say.

These reports coincided with a number of heavy, controversial attacks by US drones and helicopters on the Pakistani side of the border with Afghanistan.

The US's warning to Americans to be vigilant in Europe added fresh impetus to the scares. The Foreign Office upgraded its threat warning to Britons going to France and Germany, although the terror threat level in Britain remained the same.

European officials again made it clear yesterday they were "irritated" with the US for leaking stories before they could gather more intelligence. There was no evidence that a plot was imminent, and intelligence was described by a well-placed Whitehall official as "ill-defined".

One of those providing information is an Algerian informant – who may have been behind the decision twice recently to evacuate the Eiffel Tower in Paris. Another possible source is Ahmed Siddiqui, a German arrested by the US in July in Kabul. And last month US Predator drones attacked a suspected plotters' base in Pakistan's North Waziristan, close to the border with Afghanistan.

An anonymous Pakistani intelligence officer told the Associated Press last week that the Predator's hellfire missiles killed Abdul Jabber, a Briton who, with his brother, was allegedly suspected of planning attacks on European cities.

British counter-intelligence officials play down any suggestion of links between the US attacks in Pakistan and intelligence pointing to potential "commando-style" assaults in western Europe. European anti-terror officials, who warned against making any such link, also emphasised they had the same intelligence as the US, since they shared it.

Yesterday's warning from the state department was part of a move to encourage the US and Europe to speak with one voice after the confusion of the past week. It was initially rumoured that the US would recommend its citizens to stay away from high-profile sites in Europe.

Instead, it simply advised that: "Current information suggests that al-Qaida and affiliated organisations continue to plan terrorist attacks," noting in particular "the potential for terrorists to attack public transportation systems and other tourist infrastructure".

The US said that "European governments have taken action to guard against a terrorist attack and some have spoken publicly about the heightened threat conditions." Yet such public comments about a heightened threat were prompted, in part at least, by stories in the US media.

Downing Street felt obliged to follow the US statement. Theresa May, the home secretary, repeated that the terror threat level in the UK remained "severe" – meaning that an attack was "highly likely".

The Foreign Office issued a new travel advice warning, in common with assessments of other large European countries, that the French and German authorities continue to consider that there is a "high threat" of terrorism. Previously the advice referred to a "general threat".