Four men jailed over a failed plot to bomb London in 2005 are launching a legal bid to overturn their convictions.
Muktar Ibrahim, Yassin Omar, Ramzi Mohammed and Manfo Asiedu were jailed in 2007 for their roles in the planned attack on July 21, 2005.
In papers expected to be lodged with legal review body the Criminal Cases Review Commission (CCRC) and at the Court of Appeal as early as Thursday, their lawyers will claim that doubts cast by a senior scientist about whether their bombs were viable were not disclosed to the defence during their trial and that their convictions are unsafe.
Channel 4 News said the papers would be lodged on Thursday, while a CCRC spokesman said: "We are told by lawyers representing (the men) that an application is imminent."
Ibrahim, Omar and Mohammed took rucksacks packed with explosives on to Tube trains and a bus in July 2005, just a fortnight after four earlier bombers had killed 52 commuters. They were all jailed for life. Manfo Asiedu backed out at the last minute and removed the battery from his bomb before ditching it in a bin in a west London park, and he was jailed for 33 years.
The plots involved virtually identical homemade devices - but the trial of the July 21 bombers heard the second set of bombs failed because the bombers had got the chemical recipe wrong.
During the 2007 trial, the defence argued the men had deliberately constructed their devices so that they would not explode.
According to reports, the bombers' new appeal will focus on concerns raised by Sean Doyle, former principal scientist at the Forensic Explosives Laboratory (FEL), a top security government facility, which carries out extensive tests on all bombs found in the UK. The results of those tests later formed a key part of the prosecution evidence.
In a witness statement, Mr Doyle says a number of FEL scientists "openly expressed concerns" relating to the work of the prosecution's expert witness, Dr Stuart Black, who argued that the bombs were viable and would have worked.
But the papers submitted by the four bombers' lawyers say Mr Doyle told the Metropolitan Police that the "methodology employed by Dr Black and the interpretation of the results may not be reliable", the BBC website reported. The lawyers for the four men will argue that there was a failure to disclose Mr Doyle's doubts to the defence, it added.