The massive investigation into the London terror attacks showed no sign of slowing last night as a further seven suspects were taken into custody.

The six men and one woman were arrested during raids in Brighton, East Sussex, in connection with the attempted bombings in the capital on July 21.

It brings the running total of those being held to 19 - among them all the men named as suspected would-be suicide bombers, including one tracked to Rome.

Following yesterday's raids, a Scotland Yard spokeswoman said: "This is a further indication of the fact this is a fastmoving investigation and we continue to progress."

Police have played down speculation they are still hunting a third suicide bomb cell. However, they are searching for the key logistical players behind the attack of July 7 which claimed 56 lives and the failed attack two weeks later.

And they have just 14 days in which to gather evidence before either charging or freeing suspects held under the Terrorism Act 2000.

A spokeswoman said: "We are searching for other people in connection with this ongoing inquiry. We are not talking about cells. We have never spoken about a third cell.

"There were quite a few other people involved in the incidents of the 7th and the 21st. It's extremely likely there will be other people involved in harbouring, financing and making the devices."

Yesterday's arrests were made at one of two residential addresses in Brighton raided by officers from Scotland Yard and Sussex Police.

The suspects were being questioned at a Sussex police station.

Sussex Police Assistant Chief Constable Geoff Williams added: "There are no known risks to local residents and no armed officers were used during this operation."

Over the past week, there have been a series of raids at addresses in London, Birmingham and now Brighton as part of the fast- paced investigation.

The people in custody are suspected of the commission, preparation or instigation of acts of terrorism, or harbouring fugitives.

Scotland Yard has been given extra time to question Yasin Hassan Omar, who was captured after being shot with a Taser stun gun in a raid on a house in the Hay Mills area of Birmingham on Wednesday.

The 24-year-old is suspected of the attempted bombing of a Victoria Line train, near Warren Street and detectives have now been given permission to carry on quizzing him until Wednesday.

Muktar Said-Ibrahim, 27, alleged to be the Hackney bus bomber, and Ramzi Mohammed, who is being linked with the attempted Oval Tube attack, are being questioned after being seized on Friday.

They surrendered to armed police after a raid at a flat on the Peabody Estate in North Kensington, west London.

Police also arrested Wahbi Mohammed, 23, brother of Ramzi Mohammed, at a raid in Tavistock Crescent, less than a mile from the Peabody Estate, on Friday.

Hussain Osman, accused of being the Shepherd's Bush bomber, is fighting extradition to Britain after being captured at his brother's home in Rome.

Also in custody in London are a man arrested in Stockwell, south London, on Friday, July 22, and two men held in New Southgate, London, on July 24 and 25. It emerged last night that police also arrested another man in Finchley, north London, on Tuesday.

Police have been granted permission to continue questioning each of these men until Tuesday.

A man held in Tulse Hill, south London, on July 23 was released without charge on Saturday night.

Three women were seized on Wednesday in Stockwell on suspicion of harbouring an offender. Two remain in police hands and the third has been released on police bail until early September.

A further man was seized in Kennington, south London, on Thursday. Two women held on Friday at Liverpool Street station in the City of London under the Terrorism Act have been released without charge.