Three men helped the July 7 bombers prepare for their attack on the London transport system with a two-day reconnaissance mission of the capital's tourist attractions, a court was told today.

Waheed Ali, 24, from Tower Hamlets, east London; Sadeer Saleem, 27 and Mohammed Shakil, 31, both from Beeston, Leeds; all deny one charge of conspiring with Mohammed Siddique Khan, Shezhad Tanweer, Jermaine Lindsay and Hasib Hussain and others unknown to cause explosions between November 17 2004 and July 8 2005.

The four suicide bombers murdered 52 people when they set off bombs on the capital's transport network in 2005.

Neil Flewitt QC told a jury at Kingston Crown Court today that the three defendants did not make or transport the bombs but they did help the bombed "in one particular and important aspect of their preparation for the London bombings."

The trio travelled from Leeds to London with Hasib Hussain, who went on to detonate his bomb on the No 30 bus in Tavistock Square, in December 2004.

There they met Jermaine Lindsay, who killed 26 people on a Piccadilly Line underground train.

In the capital they visited a series of locations which, said Mr Flewitt, bore a "striking similarity" to the locations where the bombs were detonated on July 7 the following year.

Mr Flewitt said: "It is the prosecution case that the locations visited by the defendants on the 16th to 17th December 2004 bore a striking similarity not only to the locations visited on June 28 2005 by three of the London bombers, Mohammed Siddique Khan, Shezhad Tanweer and Jermaine Lindsay, when they carried out another "hostile reconnaissance of possible targets but also to the locations at which the bombs were actually detonated less than two weeks later on July 7 2005."

Saleem and Shakil visited the Natural History Museum, the London Eye and the London Aquarium.

He told the jury that all three defendants accept they made the trip, but deny they had anything to do with the London bombings.

"Rather it is their case that the purpose of their journey was to enable Waheed Ali to visit his sister in east London. Further Sadeer Saleem and Mohammed Shakil accept that they visited the Natural History Museum, the London Eye and the London Aquarium but maintain they did so for purely social reasons."

The defendants also accept that they knew the London bombers, said Mr Flewitt. But he said: "It is their case that their friendship was entirely innocent and that they know nothing of and took no part in their plan to cause the explosions in the UK."

He told the jury that he would be taking them through the events leading up to the London bombings.

He said that the bombs were manufactured in Yorkshire and then transported to London and the bombers were captured on CCTV footage, some of which the jury will be shown later today, along the route.

Four days before the attacks Shezhad Tanweer hired a sky blue Nissan Micra from First 24 Hour Car Ltd in Leeds. At 4am on July 7 Siddique Khan, Shezhad Tanweer and Hasib Hussain drove from Leeds to Luton railway station where they met up with Jermaine Lindsay.