People across Northern Ireland have commemorated the first anniversary of the September 11 terror attacks on the United States.

Belfast paid formal tribute to all those who lost their lives in the attacks during a ceremony at the City Hall on Wednesday.

Osama Bin Laden's al-Qaeda network is believed to have been behind the attacks on the World Trade Center and the Pentagon.

Among the thousands who died were people from across Ireland while others lost friends and relatives.

A wreath was laid at the tree planted at Belfast City Hall

More than 200 people attended the ceremony at Belfast City Hall.

Among those gathered were the County Tyrone relatives of a workman who lost his life in the attacks.

A commemorative tree was planted and a plaque unveiled in the grounds of the City Hall.

The event was in memory of those who lost their lives in New York, Pennsylvania and Washington DC.

A minute's silence was also observed during the ceremony, which was led by Belfast Lord Mayor Alex Maskey, US Consul-General Barbara Stephenson and councillor Chris McGimpsey, chair of the council's policy and resources committee.

Lost relatives

The maple tree, planted in the north-eastern corner of the grounds, was donated by Belfast woman Margaret Madden, who lost a relative in the atrocity.

She was joined at the ceremony by other local people who lost loved ones.

Niall Kilpatrick from County Tyrone, whose cousin Sean Canavan was among those trapped in New York's Twin Towers, said: "It just feels as if it was yesterday rather than last year."

In Dublin, Irish Prime Minister Bertie Ahern and President Mary McAleese attended a special service in the pro-cathedral.

Firefighters paid tribute to their New York comrades

At Belfast International Airport, ministers from the four main churches held an act of commemoration at 1330 BST and hundreds of people observed a minute's silence at 1346 BST.

Firefighters across the province mirrored the tribute, remembering their US counterparts who lost their lives while trying to save others.

A silence was also observed at City of Derry Airport.

At the Bloody Sunday Inquiry in Londonderry, the judges, barristers, families and people in the public gallery stood in silence in the hearing chamber.

President McAleese observed a minute's silence at that time when she visited County Fermanagh.

Later on Wednesday there was a special service at Clonard Monastery.