Britain is remaining on a 'critical' level security alert as police continue to investigate an alleged plot to blow up ten transatlantic flights.

Police are continuing to question 24 people, reportedly all Muslims, in connection with the plot, which would have targeted flights between Britain and the US.

It has been reported that nineteen of those arrested have had their UK assets frozen. These suspects have been named by the Bank of England. They include a 17-year-old and three men who are believed to be Muslim converts - Abdul Waheed, who was previously known as Don Stewart-Whyte, Ibrahim Savant, who reportedly changed his name from Oliver, Umar Islam.

Economic Secretary to the Treasury, Ed Balls, said that the Treasury had taken the decision to freeze the suspects' assets on the advice of the police and security services.

On Friday, Home Secretary John Reid said that the security threat level would remain at 'critical'. He said: "More than ever we need to draw on the tolerance and resilience of all parts of our community in the days ahead.

"This is a common threat to all of us and we should respond - all of us - with a common purpose and common solidarity. This is in the nature of the British people."

On Thursday night, it was revealed that seven people were arrested in Pakistan last week in connection with the alleged plot. Two British nationals are understood to be among those arrested.

It has also been reported that police are still searching for five other suspects who remained at large.

The plot is understood to have involved plans to detonate liquid-based explosive devices, concealed in hand luggage carried on board flights, while the planes were in the air. It is thought that the devices would have been ignited using detonators disguised as electronic devices such as a camera or a mobile phone.

Searches are continuing at addresses in east London, Buckinghamshire and Birmingham in connection with the plot.

Thousands of air passengers faced delays and cancellations in airports across the UK on Thursday as a result of the alleged plots and more delays were expected on Friday.

All British Airways long-haul flights are understood to be going ahead, except for flights to New York, LA, Washington and San Francisco, 70% of short-haul and domestic flights are also expected to go ahead.

However, easyjet and Ryanair are understood to have cancelled a number of flights.

Delays are expected across the UK due to Thursday's disruption and passengers are advised to check with airlines and airports before setting off on their journey.

Hand luggage restrictions also remain in place. Passengers will only be able to take essential items, such as wallets and purses, passports, medicines, glasses, baby items, sanitary items and tissues, on board the plane, carried in transparent plastic bag.

(KMcA)