Dignitaries joined members of the public in the congregation

The Prince of Wales, Prime Minister Tony Blair and leaders of the main opposition parties are attending, as well of hundreds of Catholics.

The Vespers of the Dead is being led by Cardinal Cormac Murphy-O'Connor.

Mr Blair delayed naming the date of the general election for 24 hours because of the Pope's death, while the prince delayed his wedding.

Delays

The service began about 1630 BST, with Prince Charles and his bride-to-be Camilla Parker Bowles attending.

Mr Blair delayed naming the date of the general election for 24 hours

Clarence House announced on Monday that the couple would postpone their Friday wedding until Saturday as a mark of respect for the Pope.

The prince cut short his Swiss skiing holiday to attend the service, and he will also attend the funeral in Rome.

They have been joined in the London congregation by other British VIPs including Tory leader Michael Howard, Liberal Democrat leader Charles Kennedy and Baroness Thatcher.

Foreign Secretary Jack Straw, Health Secretary John Reid, Chancellor Gordon Brown, Education Secretary Ruth Kelly and House of Commons speaker Michael Martin are also at the service, alongside members of the public.

A man of true and profound spiritual faith, a shining example of what that faith should mean Tony Blair Blair pays tribute Leaders pay tribute to Pope Criticism of late Pope's views

Other top politicians at the service include London mayor Ken Livingstone and Lord Chancellor Lord Falconer.

Former Prime Minister John Major is also there together with former Tory leader Iain Duncan Smith.

An hour-and-a-half before it was due to begin, about 200 members of the public were queuing up outside the cathedral to attend the service.

Victoria Akingode, from Nigeria, said: "Personally, I felt his death was expected but it was sad, although also happy because he is going to rest."

It was right for us to come and pay our respects Lorraine Welch

Lorraine Welch, from Sussex, said it was a "very sad time in the life of the Church".

"This was such a long papacy that has been so full of special moments," she said.

"It was right for us to come and pay our respects."

Cardinal Murphy-O'Connor is due to leave London after the service and fly to Italy from Heathrow Airport just after 2000 BST.

As well as attending the funeral, his trip to Rome will include helping to choose a successor to John Paul II.

He will be joined at the funeral by Mr Blair and Archbishop of Canterbury Dr Rowan Williams who had been due at the royal wedding before its postponement until Saturday.

Influx expected

Scotland's religious, political and civic leaders will pay their own separate tribute to the Pope on Monday evening in a Requiem Mass at St Mary's Cathedral, Edinburgh.

And in Northern Ireland, a Vespers for the Dead service will be held at St Peter's Cathedral in west Belfast and a Diocesan Mass in St Patrick's Cathedral in Armagh.

In the Vatican, the body of Pope John Paul II is being taken to St Peter's Basilica, where hundreds of thousands of members of the public are expected to file past.