Previously unseen surveillance footage of two of the July 7 London suicide bombers meeting a "committed terrorist" was shown on Wednesday to a court where three men accused of helping them are on trial.

Mohammad Sidique Khan and Shehzad Tanweer, two of the four British Islamists who killed 52 commuters in the 2005 attacks, were shown walking down a road in east London with Waheed Ali, who is accused of involvement in the plot.

The covert film was made in March 2004 by the security services who were monitoring another man, referred to as Ausman, who was described by prosecutors as a "committed terrorist".

In the film, Ali, 24, is seen wearing a baseball cap walking in front of the bearded Khan with Ausman wearing a white shirt and Tanweer a woollen hat.

Kingston Crown Court has already been told that Ali and co-defendants Mohammed Shakil, 31, and Sadeer Saleem, 27 are accused of helping the July 7 bombers scout for potential targets in the capital.

During a reconnaissance weekend seven months before the bombings, two of the accused visited the London Eye, the Natural History Museum and the London Aquarium, prosecutors said.

The court has also heard the men had extensive contact with the bombers, which had been uncovered through mobile records, fingerprints on documents, family videos and surveillance.

Ali, Shakil and Saleem, from Beeston, Leeds, all deny a charge of conspiracy to cause explosions and say that although they knew the bombers, their friendship was innocent.

The trial continues.