Authorities in Britain and Pakistan are focusing their attention on two brothers in their investigation of a plot to blow up U.S.-bound flights from Britain.

One brother, Rashid Rauf, is under arrest in Pakistan. Authorities there allege the suspect is a key figure in the investigation with links to al-Qaida in Afghanistan.

The other brother,Tayib Rauf, is among 23 Britons of Pakistani descent being held by police in Britain.

British and Pakistani officials say the foiled plot involved plans to detonate liquid explosives aboard as many as 10 airliners.

Authorities in the United States say they are looking for possible U.S. ties to the conspiracy.

British investigators say police made the arrests Thursday after someone in Pakistan called conspirators in Britain urging them to immediately carry out their plan.

Saturday, a coalition of British Muslim groups and politicians said Britain's foreign policy on Iraq and Lebanon is fueling extremism that threatens all civilians.

In an open letter to British Prime Minister Tony Blair, the coalition urged the government to do more to fight terrorism, while taking care not to target innocent civilians.

The British government rejects the accusation.

Britain's probe into last week's terrorist plan involves the search for possible links to July's suicide bombings on London's transport system that killed 52 people and wounded hundreds more.

Some information for this report was provided by AP and Reuters.