"Remember that every day when you put on your uniform the citizens of Baghdad will look to you to do the right thing," US Army Brigadier General Curtis Scaparotti told them.

He was speaking at a ceremony held in the capital's police academy, just a few hundred metres (yards) from the spot where a car bomb on Monday ripped through a police parking lot and killed an officer.

Scaparotti and the Baghdad police chief, Hassan al-Obeidi, shook the graduates' hands and handed them their Transition Integration Program diplomas as they filed past, to the rhythms of bagpipes and drums played by a police band.

US army helicopters hovered overhead, and heavily armed troops watched from the rooftops above the courtyard ceremony to provide protection for the senior army officers present.

The three-week course, the third so far in Baghdad, aimed to enable the Iraqi officers to "deliver law enforcement service to the citizens of Baghdad in a more humane and dignified way," according to an army statement.

It was provided by a US military police unit normally based in San Diego, California, and was due to be supplemented by further training later in the year.

"I learned a lot," said proud graduate Sergeant Salah Al-Ridha. "We learned about human rights and respect between the policeman and the citizen. None of that existed before."

Ridha, like most of the graduates Thursday, was a member of the police during Saddam Hussein's lengthy reign.

The course he attended was part of the US-led coalition's push to reform of the once-dreaded Iraqi police force and have it take over many security and policing matters from the military.