Revealed: London bomber's links to Briton in suicide attack on Tel Aviv

Leeds man who blew up train at Edgware Road was associate of conspirators who murdered three in Israel bar in 2003

The Independent on Sunday has learnt that Mohammed Sidique Khan, 30, who carried out the Edgware Road bombing, was friendly with Omar Sharif, one of two Britons who plotted a joint suicide attack in Israel in April 2003.

The disclosure comes as police continued their investigation yesterday into possible links between the four suicide bomb attacks on 7 July and the devices used in the botched attacks last Thursday. One theory is that the explosives used last week were either part of the same batch as those used on 7 July or made to the same formula - using commonly available chemicals to create the home-made explosive acetone peroxide.

Security experts believe Thursday's devices may have failed to explode because the explosives had degraded. Acetone peroxide is known to deteriorate quickly. Police now have samples from last Thursday's attacks to compare to unused explosives found in Leeds 12 days ago.

Police attempts to uncover the 7 July bombers' network of terrorist contacts are focusing on Khan's relationship with Sharif. Despite pre-recording a "suicide bombers" video in advance, Sharif failed to detonate his device; but his co-conspirator Asif Hanif carried out his attack, claiming three lives at Mike's Place in Tel Aviv. Sharif ran off, but his body was later washed up on a nearby coast.

It is now thought that Sharif's family lived in Leeds before they moved to Derby and that he went to the same mosque in Beeston as Khan, who was brought up in the area before moving to Dewsbury.

A possible link emerged last week after it was disclosed that Khan had visited Israel for a day in February 2003, raising suspicions that he had been on a reconnaissance trip for Sharif and Hanif, both of Pakistani descent.

As this paper disclosed last week, Khan is also believed to be linked to al-Qa'ida. He was identified by a Pakistani-American computer expert, Mohammed Junaid Babar, 29, who was arrested after attending al-Qa'ida summit meetings in Pakistan. These links strengthen suspicions that Khan was the dominant influence on the other two bombers from Leeds, Hasib Hussain, 18, who carried out the No 30 bus bombing, and Shahzad Tanweer, 22, who carried out the Aldgate Tube attack.

As the investigation into the London bombings continued abroad, police inquiries in Leeds were winding down. On Friday, the Metropolitan Police released without charge a 29-year-old man arrested on 12 July in Beeston under terrorism legislation. It is believed the man is Navid Fiaz, who held keys for the Hamara youth centre and Iqra Islamic bookshop, where the bombers are said to have congregated.

Locals believe Mr Fiaz may have been able to help anti-terrorism officers piece together key elements of the plot, and links between the bombers, because he is one of the area's most trusted youth and community activists.

While police carried out a controlled fire on Thursday to destroy explosive traces at the plotters' "bomb factory" several miles away in Alexandra Grove, the scaffolding and white plastic sheeting covering the bombers' houses and a local Islamic bookshop in Beeston was being taken down. Police guards on the properties have also gone.

The Iqra bookshop, the only Islamic bookshop in Leeds, was alleged to be a focus of radical activity in the area and to have had links to Saudi Arabian Islamist groups. Police raided it nine days ago. However, Muslim activists have denied any hardline ties and one of the bookshop's workers, who refused to give his name, insisted that the most radical material it had was from the Stop the War Coalition protesting about the Iraq war. "There was nothing there inciting terrorism, any more than people would be incited to terrorism by watching the bombings on TV," he said.

Only the lower-storey windows on Tanweer's family home remained boarded up; his family is still living under police protection elsewhere. Fears that the bombers' homes would be targeted in retaliation escalated after an attempted arson attack on Thursday on the home of Jermaine Lindsay, who carried out the King's Cross attack.

Petrol and diesel was allegedly found near the house on North Road, Aylesbury, Buckinghamshire, on Friday morning. Yesterday, a teenager was charged with arson.

Beeston locals said yesterday that life was returning to normal. "It's all calmed down," said one. "I'm surprised how quickly that's happened."

Councillor Khizar Iqbal said Dewsbury was also far less unsettled than people had feared. Both Leeds and Dewsbury have a history of far-right and neo-Nazi activity.

However, one local Beeston resident, Asif, said there were still fears that far-right groups could attack now that most of the police had left.

Meanwhile, several hundred anti-war activists and Muslim activists staged three "Walk for Peace" marches into Leeds city centre yesterday afternoon. Protesters denounced the terrorists who planned the 7 July attacks, and insisted they had no claim to be acting for other Muslims.

* A leader of the Stop the War Coalition, Lindsey German, has consulted lawyers about suing the satellite channel Sky News because she believes it implied that she might have been the fourth London suicide bomber. Sky appears to have mistaken the name of the Jamaican-born bomber, Jermaine Lindsay, with hers when there was initial confusion over his identity.