It is the second suspect to be released by the authorities, since British police and intelligence officers carried out pre-dawn raids on the suspects’ homes in London and other British cities and towns.
Under British anti- terrorism laws suspects can be held without charge for no more than 28 days, a process that is subject to regular court approval. Police have been granted more time to question 23 of the suspects detained, 21 of those can be held until August 23, the other two until August 21.
Few details have been officially released about the alleged plot, but it appears to have involved suicide bombers smuggling liquid explosive disguised as drinks on to US airliners, detonating them with electronic devices mid- flight.
Pakistan connection
Mr Reid refused to confirm or deny if Britain was seeking the extradition of suspects -- two British and five Pakistani -- from Pakistan, but he expressed his "gratitude" to Islamabad for its role in the investigation.
One man who is “apparently related” to one of the British suspects is being held in Islamabad.
Europe threat
Meanwhile, the British Home Secretary, John Reid, has that Europe as a whole is facing a "very real" and "persistent" risk of a devastating attack.
After meeting with European Union interior ministers in London to map out a common strategy, Mr Reid said, "What's clear to all of us is that we face a persistent and very real threat across Europe."
The European Commission promised to introduce a series of measures to strengthen security at airports, boost cross- border intelligence sharing and tighten controls on explosives before the end of December.
EC Vice President Franco Frattini, who was also present at the London meeting, suggested steps to encourage what he called "a European Islam", including the training of imams, and the blocking of Internet websites deemed to be inciting terrorism.
Cost counting
As the immediate threat at airports wanes, airlines are beginning to count the cost of the alert – and consider who should pay. British Airways PLC is leading a growing campaign against the British Airports Authority (BAA), which many carriers claim was ill-prepared for the cancellations and delayed flights.
A joint compensation claim against BAA, which operates seven airports around Britain including Heathrow, Stansted and Gatwick, could run as high as 300 million pounts (A$745 million), the figure based on analyst estimates of daily losses.
Airlines claim that BAA was too slow to respond, with the alert crippling airport operations and that BAA has struggled since then to get flight schedules back to normal.
BAA, which was recently acquired by a Spanish construction giant, has called those accusations "neither fair nor accurate".
"The fact is that Heathrow, the world's busiest international airport, is at the best of times significantly overstretched because of the difficulties over many years of securing permission to grow capacity at the airport," BAA said in a statement.
"The scale and suddenness of the measures imposed last week could not be managed without significant disruption," it added.