“The Western Australian Police executed a number of search warrants overnight and interviewed four men,” the Australian Broadcasting Corporation (ABC) said on Friday.

They have also seized computer and communications equipment for further forensic examination. “Officers are questioning other doctors to try to establish any connections with the attempted attacks in Glasgow and London,” Federal Police Commissioner Mick Keelty was quoted as saying by ABC news.

“I want to stress at this stage that nobody has been charged with any offence...,” he said.

Meanwhile, a media report said on Friday that the failed bombing plots in the UK were carried out with the blessings of al-Qaeda leader Osama bin Laden.

“It was an established fact from Day one that al-Qaeda was behind this and it was planned by its followers in Great Britain with bin Laden’s blessings,” The Times quoted a “foreign” intelligence source as saying.

British security officials were more guarded, saying it was too early to say whether the plot was masterminded by some foreign hand or hatched in Britain.

“The warning an al-Qaeda leader in Iraq delivered to Canon Andrew White, a British cleric working Baghdad, in April certainly suggested that he knew of the doctors plot,” the source said. An al-Qaeda leader reportedly told White, “Those who cure you will kill you.”

British Prime Minister Gordon Brown said on Friday that investigators are close to “getting to the bottom” of the cell behind the failed attacks. “We want people to know that we have acted very quickly to deal with potential future incidents,” he told the BBC.

The Prime Minister has also spoken of al-Qaeda links to the plot, and British intelligence services are working with counterparts around the world to establish the extent of suspected involvement by Osama bin Laden’s network or its Iraqi arm.

A week after the intended bombings in London and Glasgow, law enforcement officials say the evidence emerging is that the two doctors were the main operatives of a network of other medical professionals. Much still remains unknown about the plot, including whether it was planned inside Britain, in Iraq or elsewhere. Altogether, eight suspects in the case are in police custody. All are foreigners working for Britain’s state health system.

British investigators have concluded that the two men who carried out an attack at Glasgow International Airport last Saturday had sped there after a failed attempt to bomb a nightclub in central London, a British security official said on Thursday.

And for the first time, a neighbour and the police have provided descriptions of the two men held—Bilal Abdulla and Khalil Ahmed—saying they may have lived together intermittently in this placid neighbourhood outside Glasgow and that a Jeep Cherokee similar to the one used to crash into an airport terminal had been seen speeding around in the weeks before the botched bombing.

The manager of a local cab company said on Thursday that on two occasions from end-May to end June a taxi picked up the two men together, suggesting they could have been sharing a home here from time to time.

Charles MacPherson (34), who lives in a housing development near the Neuk Crescent cul-de-sac where Abdulla rented his home, said on Thursday that recently the neighbourhood’s tranquility had been roiled by a speeding vehicle resembling the one used in the Glasgow attack. “Someone has been driving this green Jeep at high speeds up and down the road,” he said. “It stands out because it’s the only Jeep in the area.”