British police on Sunday arrested six people in connection with the failed terror attacks on London as ministers prepared to look into how some suspects could fly out of the country during Scotland Yard's largest manhunt.
House of Commons leader Geoff Hoon said ministers will be considering claims that passport checks were inadequate after the July 21 failed bombings, which possibly allowed Osman Hussain, 27, to flee to Italy before being arrested in Rome.
Hussein's lawyers meanwhile indicated he would fight extradition from Italy. "I'm aware that the Home Office will be looking at that. Certainly in recent times there has been enhanced security for those leaving the country as well as for those coming into the United Kingdom," Hoon told the British Broadcasting Corporation about the concerns that checks were lax in Waterloo railway station.
Police questioning the arrested suspects probed their possible links with Saudi Arabia and Italy.
The six new arrests were made after two raids in Sussex. Searches are under way at the properties.
It is believed Ethiopia-born Hussain, also known as Hamdi Isaac, left Britain on a Eurostar train from Waterloo on 26 July, travelling to Paris and Milan before landing in Rome.
Lawyers of the suspected bomber of a train near Shepherd's Bush station in west London said he had not agreed to fast-track the lengthy legal process, indicating he may fight extradition.
He is the first to whom Italy is applying the rules of the newly created European Arrest Warrant, allowing speedy transfer of suspects between EU states.
Scotland Yard forensic teams are studying items seized from 14 addresses in London and two in Birmingham. Hoon said extra passport checks were being considered. The Tories said action on border controls was 'vital.'
"It's one of those arguments that we have used to support the idea of identity cards, because it is vitally important that we are able to say who is in the United Kingdom at any given time."
Earlier, shadow home secretary David Davis said: "This demonstrates the vital and immediate necessity for the government to get a grip on our porous borders, both in terms of people coming into the country and in terms of people leaving."
Reports on Sunday said intelligence about a cell with access to explosives and which plans to unleash a "third wave" of attacks was the trigger for last Thursday's unprecedented security exercise- the biggest since the second world war- in London which saw 6,000 police, many armed, patrolling across the city.
Meanwhile, Italian police arrested a brother of Osman Hussain, named as Fati Isaac, in Brescia, in northern Italy on sunday, ANSA news agency reported. Another brother, Remzi Isaac, was held along with Hussain on Friday.
Yasin Hassan Omar, Muktar Said Ibrahim and Ramzi Mohammed, the other men suspected of carrying out the attacks on 21 July, are being questioned in London.
A fifth suspect, also arrested during Friday's raids, is also being questioned.
