LONDON — Four of six men accused in a failed attempt to blow up portions of London’s public transit system in 2005 were convicted yesterday of conspiracy to commit murder. The jury will continue deliberations on the fate of the other defendants today.

The panel unanimously rejected the defense contention that the bombs, which failed to explode, were meant to scare the public and prompt government officials to reconsider British involvement in Iraq and Afghanistan.

“The failure of those bombs to explode owed nothing to the intention of these defendants. Rather it was simply the good fortune of the traveling public that day that they were spared,” prosecuting lawyer Nigel Sweeney said in court.

Prosecutors linked the failed bombings on July 21, 2005, to successful suicide attacks on the London transit system two weeks earlier, which killed 52 people and injured hundreds.

The jury convicted Muktar Said Ibrahim, 29, Ramzi Mohammed, 25, Yassin Omar, 26, and Hussain Osman, 28. The panel still must determine the fates of Manfo Asiedu, 33, and Adel Yahya, 24.

Mr. Ibrahim, the group’s self-confessed ringleader, targeted a bus in East London. He escaped during the commotion that followed the loud bang of his detonator going off.

Messrs. Mohammed, Omar, and Osman attempted to set off explosives in subway stations. Mr. Mohammed escaped after he was chased through the Oval station by commuters, including a man in his 70s. Messrs. Ibrahim and Mohammed were caught in a police raid eight days later.

Mr. Omar slipped away from authorities in the Warren Street station. The next day he fled to a predominantly Muslim neighborhood in Birmingham disguised as a woman, wearing a full-length burqa and carrying a white handbag. He was later arrested while standing in a bathtub fully clothed.

Mr. Osman fled to Rome, where he was extradited to Britain.

The men were inspired by the bombings of July 7, 2005, according to the defense. After searching the Internet, Mr. Ibrahim said he found instructions for building bombs through a Web site and intentionally changed the procedure so that the explosives would not detonate.

Prosecutors showed evidence, however, that Mr. Ibrahim had spent three months training in Pakistan in 2004 at the same time as Mohamed Sidique Khan and Shahzad Tanweer, two bombers who died in the July 7 attacks. There he learned to build bombs similar to those used by Messrs. Khan and Tanweer, the prosecutors said.

The handmade explosives, conjured on a kitchen stove in London, included household ingredients such as flour, hydrogen peroxide, and acetone, which is found in nail polish remover. The would be terrorists placed the bombs in buckets and glued nails, screws and other sharp objects to them as shrapnel.

Forensics experts said the unique composition of the explosives linked the two conspiracies. “Prior to July 2005, we had never had this sort of material submitted to the laboratory before,” Claire McGavigan, a scientist at the Forensics Explosives Laboratory, testified in January.

Ms. McGavigan said the homemade shrapnel would have caused massive injuries.

“They would have quickly propelled away from the explosion, very fast and very hot,” she said. “Any fragments could embed themselves in a person and cause serious injury.”

All six men emigrated from Africa during childhood.

Mr. Ibrahim arrived in Britain in 1990 after escaping war in his native Eritrea. The prosecution said he soon turned militant, attending Muslim services at Finsbury Park Mosque in London, where he heard the radical teachings of fundamentalist cleric Abu Hamza al-Masri. In 2003, he traveled to Sudan to receive military training and to learn to use rocket-propelled grenades, according to court testimony.

A year later, police questioned him at Heathrow Airport before he boarded a flight to Pakistan. He was carrying a first-aid kit, a sleeping bag and $6,000, and he said he was on his way to a friend’s wedding.

Without sufficient cause to hold him, authorities allowed Mr. Ibrahim to board a later flight.