A young British Muslim woman from the East End was described today as an "innocent and blood-stained martyr" as her family laid her to rest in the first funeral of any of the victims of last week's London bombings.

Police investigations into the attacks gathered pace as it emerged that one of the London bombers visited the Houses of Parliament as a guest of a Labour MP.

In Cairo, an Egyptian chemist wanted for questioning has been arrested. Officials there said that he had denied any involvement in the attacks in which at least 54 people died.

Magdi el Nashar, a 33-year-old who had been teaching at Leeds University, left Leeds two weeks ago after telling his landlord that he had visa problems. Police sources have since said that materials have since been found at a flat rented in his name in the Leeds suburb of Burley which suggest it was used as a bomb factory.

Egyptian officials would not say today when exactly Mr el-Nashar was detained but one Interior Ministry official said: "El-Nashar denied having any relation with the latest events in London. He pointed out that all his belongings remained in his apartment in Britain."

The Egyptian's arrest is another possible breakthrough by police investigating the co-ordinated attacks on three Tube trains and a London bus, carried out by four British Muslim men who appear to have died in the attacks. Sir Ian Blair, the Metropolitan Police Commissioner, said he might ask for Mr el-Nashar to be extradited from Egypt.

As Sir Ian visited mosques around the city in a drive to persuade Muslims to become actively engaged in the fight against terrorism, the family of Shahara Islam, a 20-year-old from Plaistow, buried her in a private ceremony.

A statement from her family paid tribute to a simple girl who had been at the wrong place at the wrong time. It read: "Today our dear daughter, cause of our joy and light of our eyes - our Shahara - is returning to her Lord, an innocent and blood-stained martyr. She was an Eastender, a Londoner and British, but above all, a true Muslim and proud to be so.

"She was a simple girl, from a simple family who led a simple life. Unfortunately she was at the wrong place at the wrong time on that unfortunate day. The flame of her life has been cruelly extinguished from this beautiful young woman in her prime, who had the whole world ahead of her."

British police have been seeking news of Mr el-Nashar since he emerged as the tenant of the flat where explosives were found in Burley, in Leeds, on Tuesday. Those explosives were earlier identified as triacetone triperoxide (TATP), a substance commonly used by suicide bombers in the Middle East that is also known as "Mother of Satan".

TATP is readily made from chemicals available over the counter, although its manufacture is very dangerous because it is so unstable. This is the same type of explosive that Richard Reid had in his shoes when he attempted to blow up a transatlantic flight in 2001, as did the Gloucester "shoebomber" Sajid Badat who decided not to go through with his mission.

The discovery was thought to provide another link in the chain of evidence connecting the perpetrators of the bombings to al-Qaeda.

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