Counter-terrorist police have raided three houses in Keighley in the wake of the attacks in London and Glasgow.

The officers went to the houses after tip-offs about men in Lanashire buying propane gas canisters - similar to those used in the terror attacks.

But, rather than terrorism it is understood the gas was allegedly being used in connection with growing cannabis. The investigation is now being classed as "criminal".

Police spent most of yesterday searching the houses and announced later that hydroponics equipment, which is used for growing plants in water, was yesterday afternoon seized from the house in Bradford Street.

Documentation, such as driving licences, were taken from all three addresses and a computer from Parson Street.

The West Yorkshire Counter Terrorism Unit led the operation to raid the houses in Highfield and Guard House, around 9pm, on Tuesday.

The unarmed team was accompanied by Keighley's neighbourhood policing team and local community leaders when they knocked on doors in Parson Street, Bradford Street and forced their way into an unoccupied house in Whin Knoll Avenue.

The community leaders had earlier been invited to Keighley Police Station for a briefing.

It was also confirmed yesterday that the action followed the arrest of two men in Blackburn, initially believed to be related to last weekend's terror attacks in London and Glasgow.

Lancashire Police had searched an industrial unit following a tip-off from the public.

The suspects are believed to have been seen buying gas canisters. But a search of the Blackburn premises revealed signs of possible cannabis cultivation. Yesterday the two men were being held on suspicion of drugs offences rather than under anti-terrorism legislation.

One of the Keighley leaders invited to the pre-raid meeting, Sajid Khan, yesterday praised police for keeping the community reassured and informed.

He said: "They were very, very sensitive in the way they went about this." Families in the two Lawkholme houses were moved to temporary accommodation.

Paramedics were on standby during the raids because police knew one of the occupants had a heart condition. More detailed searches of the properties were taking place yesterday. Keighley police increased their uniformed presence around the town following the raids. Supt Gary Baker, from Keighley police, said he was grateful for the support and understanding of the local community during Tuesday's operation.

He said: "We did our best to keep them up-to-date, including inviting representatives to the scenes with officers to see what we were doing at first hand. "Our role has been to support the Lancashire Police inquiry after they made arrests under the Terrorism Act, based on the information they had at the time. "Our approach has been relatively low-key and officers approached the houses quietly and knocked on the doors to gain entry.

"We understand that these are difficult times for all our communities and people need to remain vigilant, and where they suspect any suspicious activity report it to their local police or the anti-terrorism hotline A police spokesman said: "We realise these are sensitive times.

"On this occasion a member of the public who had their suspicions aroused rightly contacted police. "Anybody with local information concerning possible terrorist or extremist activity should contact us."

Police asked people to remain vigilant and if they saw anything suspicious to phone local police or the anti-terrorism hotline on 0800 789321. Details of local specialist officers can be found on the Internet by logging on to the force's website at www.westyorkshire.police.uk/npt/