British officials last night played down the possibility that Britons were involved in the attacks on Mumbai.

India's first minister was reported to have claimed that two of the arrested gunmen were British-born Pakistanis, and UK authorities quickly said they were investigating the reports.

But the Foreign Office later said that the deputy high commissioner in Mumbai had talked to Indian authorities, who said there was no evidence that any of the terrorists, shot or detained, were British.

A spokesman said: "We have spoken to Indian authorities at a high level, and they have said that there is no evidence that any of the terrorists either captured or dead are British."

He added that the Indian chief minister had "said no such thing privately or publicly", despite reports to the contrary.

Intelligence sources also said that they had seen nothing to suggest that the claim, attributed to the chief minister Vilasrao Deshmukh, was correct.

Last night reports in Britain claimed that security forces in India had found BlackBerry handheld devices which allowed the terrorists to monitor international news websites.

An officer from the Indian special forces units who were in action during a siege of Mumbai's Jewish centre had reportedly said that the devices had contained "content from the English media".

Elsewhere, reports suggested that up to seven of the attackers could have been British and that they had links with Yorkshire.

However, speculation linking the attackers with Bradford, West Yorkshire, was rejected by the Leeds-based Counter Terrorism Unit.

A statement from sources in the force said: "At this stage we are not in receipt of any intelligence or information linking the events in India to our area."

The Times reported last night that it had been told by Patrick Mercer MP, a former Tory security spokesman, that he had been given information that at least two of the terrorists had credit cards and other identifying documents which linked them to Dewsbury, West Yorkshire. He also said he had been told that the terrorists arrived with only basic communications - but had then seized mobile phones and BlackBerry devices from their hostages and used them to contact each other and to monitor world reaction.

Earlier in the day the home secretary, Jacqui Smith told reporters: "I think it's important that we make judgments on this on the basis of actually the fullest possible knowledge and intelligence, and that's obviously what we are working on at the moment." British authorities had "no knowledge" of anyone with a UK passport being among the gunmen who had been either killed or captured, she added.

Gordon Brown also warned against jumping to conclusions. Following a phone conversation with his Indian counterpart, Manmohan Singh, the prime minister said: "At no point has the prime minister of India suggested to me that there is evidence at this stage of any terrorist of British origins, but obviously these are huge investigations that are being done and I think it will be premature to draw any conclusions at all.

"We remain steadfast and firm, standing with India and all other countries against any form of terrorist activity, and we will be vigilant in both helping the Indian authorities and in making sure that in every part of the world we support those who are fighting terrorism."

British anti-terrorist officers are liaising with their Indian counterparts, and officers are now in Mumbai. They are understood to include include terrorism experts and family liaison officers.

Officers are also meeting Britons returning on flights to London's Heathrow Airport and handing out leaflets appealing for information.

A German MEP caught up in the attacks said she had heard that British nationals were among the terrorists involved in the killings in Mumbai. Erika Mann, part of a trade delegation of MEPs from Brussels staying at the Taj hotel, said she had escaped through an underground passage. She said: "The attacks appear to have a European dimension. We have heard from journalists and other people we were with that English citizens took part in the attacks and were killed in the hotel."