New York - New York Mayor Bill de Blasio and police commissioner Bill Bratton on Monday criticised dozens of officers for turning their backs on the mayor at the funeral of a murdered policeman.De Blasio said the action by "some individual officers" disrespected the families of Detectives Wenjian Liu, aged 32, and Rafael Ramos, aged 40, who were shot dead on 20 December."I cannot understand why anyone would do such a thing in a context like that," he told a news conference a day after Liu's funeral."They were disrespectful to the people of this city who in fact honour the work of the NYPD," he added.Hundreds turn awayTens of thousands of police officers attended funerals a week apart for Liu and Ramos, who were killed by a black gunman claiming to be avenging the deaths of African-Americans during recent confrontations with police.At Ramos's funeral last week, hundreds of officers turned away from the mayor and a small number defied instructions from Bratton by repeating the action at Liu's funeral on Sunday.Some officers accuse de Blasio of inciting the shooting over remarks about police relations with black Americans and were enraged that he counsels his son to be careful around officers.Bratton said Monday that he hoped his instructions to the 35 000 strong New York police force had encouraged the vast majority to behave.He said the protest was carried out by only a few hundred of the more than 20 000 police officers who attended the funeral.Officers 'selfish'He accused them of "selfishness" by drawing attention away from Liu and his stricken family with the protest dominated much of the press coverage.They "embarrassed themselves" by staging "a labour action," he said."You don't put on the uniform and go to the funeral and engage in a political action. I'm sorry but I feel very strongly about that I do," he said."I don't share the perspective that the mayor had blood on his hands or that any of his actions led to the deaths of the two officers," Bratton added.