The charges brought on Tuesday, including conspiracy to murder, against Nabeel Hussain, Mohammed Yasar Gulzar and Mohammed Shamin Uddin, bring the number of people charged to 15.

The three men were among the 25 people originally seized by police in raids on August 10, five of whom have been released without charge.

Police also have warrants to question the remaining five until Wednesday. Under British anti-terror laws, suspects can be detained for up to 28 days without being charged, subject to regular court approval.

Security at British airports was stepped up to unprecedented levels in the aftermath of the police raids on August 10, with the country upgrading its threat level to "critical".

The suspects were allegedly planning to smuggle seemingly innocuous liquids on to planes with the intention of assembling them into bombs on board. The alleged plot was described by one senior police officer as "an attempt to commit mass murder on an unimaginable scale".