The family of three men arrested during a major anti-terror operation protested their innocence today.

Ansar Khan, 48, a taxi driver who works at Gatwick airport, said there was "absolutely no truth" in the allegations against his son, 18-year-old Ahmad Khan.

He also dismissed the possibility that his nephews Omar Khyam, 22, and Shujah Khyam, 17, were involved in terrorist activity.

All three were arrested during early-morning raids in Crawley yesterday.

The three had been linked to Al-Muhajiroun, a hardline Muslim sect committed to waging holy war on the West.

At his parents' home in Langley Drive, Crawley, Mr Khan today said police officers had acted "like terrorists" when they arrived at 6am.

He said: "They explained nothing. The warrant was shown after 20 minutes and they wouldn't even let me answer the phone."

Mr Khan said his son had been tearful as he was dragged from the house and kept crying for his mother.

Mr Khan had argued with police, and said their behaviour made him "very angry".

He had refused to leave the house when they began searching it: "I kept watching the Test match until lunchtime. They weren't going to make me leave my own home."

Mr Khan said operatives from MI5 had approached Omar and Shujah, and told them they should go to Pakistan.

He said: "MI5 came to them and said they should leave. They had two meetings."

Mr Khan said the family had bought tickets for the boys to return to Pakistan and they had been due to fly out soon.

Mr Khan said his son Ahmad was a "very quiet boy".

He added: "He won't talk much. He is a very straightforward kid."

He said his son was a "good Muslim - better than me", who prayed five times a day.

Mr Khan criticised the teaching provided at local mosques as "wrong".

He went on: "I said to Ahmad don't go to the mosque. I said, you read books by scholars. Those books are true.

"What they tell you at the mosque is not."

The three arrested in Crawley are among eight being questioned by detectives today after 24 co-ordinated raids across the South-East.

An 18-year-old was captured in his room at the Holiday Inn at Gatwick by police from Surrey, who had earlier removed his car from the car park outside. He was described as a visitor to the UK.

The police operation followed months of intelligence-gathering centred on a self-store warehouse in west London.

A bag containing half a tonne of ammonium nitrate fertiliser, a key ingredient in the manufacture of explosives, was seized by police there.

The chemical, which requires a booster explosive to set it off, has been used in attacks in Bali, Turkey, Saudi Arabia and Africa.

Experts said the fertiliser found yesterday could have been used to produce a "spectacular" explosion on the scale of the 1995 Oklahoma bombing which killed 168 people.

It was the biggest seizure of potential bomb-making material since the IRA suspended its terror campaign in 1997.

The co-ordinated swoop is believed to have been mounted yesterday because police working on Operation Crevis feared the threat of an attack had become imminent.

Crawley residents spoke of their shock but some said the Al Muhajiroun (Emigrants) sect had become active within the community.

Members are believed to have used an internet cafe in the Langley Green shopping precinct, one of seven properties on the estate which were sealed off as police continued their investigations.

The cafe opened in January and proved a popular meeting place for young Muslims.

Raids also took place at well-kept terraced homes in Lime Close, Langley Walk, Juniper Road, Langley Drive and The Hollow.

A police officer stood guard outside a house in Juniper Road which had a blue J-registration Mercedes outside.

A neighbour in Lime Close said the raided house belonged to a man in his 40s.

Standing in front of the property, which had its front door smashed off the hinges, he said: "I am shocked at what happened.

"We have a good relationship as neighbours."

Builder Sajjad Ahmed, 40, had been renovating the house for a relative.

He said: "The Muhajiroun are religious fanatics but I don't believe they would mount terrorist attacks.

"The police have gone over the top.

"The group was centred around the internet cafe and they would go around town collecting for their cause.

"There have been concerns about Al Muhajiroun operating in Crawley.

"They have been thrown out of local mosques and were having difficulty in finding places to meet because of their beliefs."

Pinakin Patel, who runs Kandie Sweets, close to the internet cafe, said: "The people that ran it came from Pakistan. I'm from India so I did not speak to them very much.

"They opened in January after taking over the butcher's shop which had been closed for several months.

"Nobody mentioned there was anything suspicious going on at the cafe."

Yesterday's other arrests were made in Uxbridge, Ilford, Colindale, Slough and Luton.

The fertiliser was found in a 6ft by 2ft plastic bag at a storage centre in Boston Road, Hanwell, west London.

Sussex Deputy Chief Constable Joe Edwards said investigations would continue over a number of days.

He said: "We are doing all we can to minimise disruption and inconvenience to the public.

"We remain in close contact with community leaders and are deeply grateful for the continued support of all our communities.

"It is with their help and assistance that terrorism will be defeated."

Scotland Yard Deputy Assistant Commissioner Peter Clarke, head of the anti-terrorist branch and national co-ordinator for terrorism, took the unusual step of making a public statement almost immediately.

He said police were in talks with leading British Muslim groups.

He added: "We know the overwhelming majority of the Muslim community are law-abiding and completely reject all forms of violence.

"Today at both local and national levels we have been holding discussions with community leaders and other representatives to address any concerns they may have."