An Amnesty International poster campaign aimed at highlighting how the Human Rights Act has helped causes as disparate as the Hillsborough families and the Northern Ireland peace process has been banned by Network Rail as too political, the rights group has said.Amnesty said on Tuesday it was disappointed that posters booked for rail stations around the country had been pulled, even though Transport for London had run them at an underground station.Network Rail confirmed it had pulled the posters, saying they did not meet its rules on political advertising, in part because they directed people towards an online petition against government plans to scrap the act.