The youngest of the July 7 London [Images] bombers made 3 desperate telephone calls begging for help from the other members of the terror cell just minutes before he blew himself up on a bus.

The frantic last messages of Hasib Hussain, 18, are seen by Scotland Yard as vivid proof that the British-born Muslim extremists knew they were going to die in the attacks, 'The Times' daily reported on Thursday.

The teenager clearly panicked when he realised he could not get on to a Northern Line Tube to detonate his rucksack bomb as the service had been suspended because of a broken down train.

Knowing that all 4 men were supposed to synchronise the timing of the explosions, Hussain ran out of King's Cross Underground station and tried to reach his accomplices by mobile telephone.

Also read: The London Blasts

It was just before 9:00 a.m., but by then all his fellow bombers were already dead. The other 3  had triggered their devices within seconds of one another at 8.50 a.m.

According to the report, Hussain first called Mohammad Sidique Khan, 30, the alleged leader of the group, saying "I can't get on a train. What should I do?"

Then, in quick succession, he left the same message for Shehzad Tanweer and Jermaine Lindsay. Clearly agitated about his next move, he hurried away from the station.

The report quoted a police source saying 'his voice was getting more and more frantic with each call.'

Despite his rising panic, Hussain climbed onto a passing No 30 double-decker bus in Tavistock Square. Survivors remember him looking flustered as he rummaged inside the large black rucksack on his lap.

Seconds later he detonated the homemade explosive, killing 13 people. It was 9.47 a.m. -- 57 minutes after his accomplices had struck.

Forensic science experts who have examined the remains of the bombs are now certain that they were all triggered manually, which proves that the men were not duped into becoming suicide bombers.