LONDON (AP) âÄî Three men accused of helping plan the 2005 London transit bombings were acquitted Tuesday of playing any role in the plot, a blow to investigators’ hopes of convicting anyone over the worst attack on Britain since World War II. A jury in London found Waheed Ali, Sadeer Saleem, and Mohammed Shakil not guilty of conspiring to cause explosions. They were accused of working with four suicide bombers who attacked three subway cars and a bus July 7, 2005, killing 52 passengers and themselves. Prosecutors had alleged the accused took part in a test run for the attacks in December 2004, when they joined three of July 7 bombers on a trip to London. The group visited subway stations and a host of popular tourist spots, such as the London Eye observation wheel and Natural History Museum, prosecutors said. But the jury rejected claims the three men were involved in plotting the attacks. It was the second time they had been tried. A different jury failed to reach verdicts in August. Ali and Shakil were convicted Tuesday of a lesser charge of conspiring to attend a terrorist training camp. They will be sentenced Wednesday. Legal experts said the outcome has highlighted concerns about how Britain prosecutes alleged terrorists, following a series of high-profile acquittals in major trials. Prosecutors must tackle increasing public skepticism about the extent of the terrorist threat to Britain, fueled by the failures of recent police raids against Muslim communities to result in charges. “Many of these cases take months, and juries get to know and like the defendants,” said human rights lawyer Geoffrey Robertson, who was not involved in the latest case. “They begin to think they’re not so bad and they doubt the strength of the evidence against them.” Ali, Saleem and Shakil had been tried last year, when a different jury failed to reach verdicts. In another major case, Jordanian neurologist Mohammed Asha was cleared last December of involvement in botched car 2007 bomb attacks on Glasgow and London. Last October, the trial of people alleged to have plotted to bring down airliners bound from Britain to the United States also collapsed. Shakil, Ali and Saleem, who were close friends of the four suicide bombers, are the only people to have been tried in connection with the July 7 transit attacks. Police said their inquiry âÄî Britain’s largest police investigation ever âÄî is continuing. But officers say their work has been hindered by the reluctance of witnesses in Britain’s Muslim communities to come forward. Jacqui Putnam, who was injured in the blast in a subway car at London’s Edgware Road station, said the failure to bring anyone to justice has left survivors frustrated. “It was painful to follow the trial, and it is equally painful to be here, nearly four years after 7/7 and still have so many unanswered questions,” Putnam said in a statement after the verdict.