New York City paid tribute Friday to five police officers who died as a result of illness contracted while responding to the 9/11 attacks 12 years ago.

Mayor Michael Bloomberg and police chief Ray Kelly presided over the unveiling of a police memorial wall to which the names of the deceased officers were added.

The monument in Battery Park in southern Manhattan is close to the World Trade Center, which collapsed and where 2,753 people were killed in the attacks.

The five officers aged between 40 and 58 died between July 2011 and July 2012, according to local authorities.

"We owe each of them a tremendous debt of gratitude for their many years of exceptional service as members of the police department," Kelly said.

Around 65,000 people, including more than 50,000 emergency service personnel, have contracted illnesses, particularly breathing and skin conditions, as a result of responding to the Al-Qaeda hijackings in New York, Washington and Pennsylvania.

They are treated under the World Trade Center Health Program, which looks after those who responded to the attacks and survivors in the New York disaster area.

In August, the New York Daily News reported that 1,140 people were suffering from cancer contracted as a result of the attacks.