Media playback is unsupported on your device Media caption The marchers celebrated the 25th year of the annual parade in Belfast

Thousands of people have lined the streets of Belfast for the city's annual Gay Pride Parade.

Much of the attention this year focused on the campaign to introduce marriage equality in Northern Ireland.

The parade left Custom House Square at noon with the usual mixture of colour, music and performances.

The event is now in its 25th year and organisers claim that, in that time, the number of participants has grown from 100 to more than 40,000.

Image caption This year's parade was as colourful as ever

Image caption Many of the participants campaigned for the introduction of same sex marriage in Northern Ireland

Festival organisers wore t-shirts with the slogan "It's time", a reference to the continuing campaign for "full equality" in Northern Ireland.

Sarah Melville-Watson from Belfast Pride Festival said they were trying to capture the momentum that built up during the same-sex marriage referendum in the Republic of Ireland in May.

"It was a massive step forward, and in Northern Ireland we're only one small part of a country that has accepted the LGTB community fully and we're not."

Image caption Festival organiser Sarah Melville-Watson said the thousands of supporters on the streets showed the depth of support for gay rights and same-sex marriage

"This is our opportunity. We can't have that vote, but we can stand together," she said.

"You need to stop and listen to us and you need to understand that equality is the way forward."

'Open-minded'

One spectator, who moved out of Belfast more than 40 years ago, said the growth of the local Gay Pride movement was a sign of how much the city has changed.

"When I left Belfast in 1974 you would never, ever, ever imagine that this kind of thing could happen in Belfast and it's brilliant, absolutely fantastic," the woman said.

"I think it says an awful lot about how society has changed and how open-minded people have become, and I think that's all to the good."

Media playback is unsupported on your device Media caption John Barr and Gerry McGrillen explain why they believe they should be allowed to marry

Image caption The parade passes city hall

Image caption The march was as flamboyant as always

Thomas Finnegan, 53, from Belfast said: "I've been on the parades since they started in Belfast and there was only a handful of us and this is amazing to see the number of people.

"The first parades where scary, there was only a handful of us and you were frightened, because there was a big fear factor to see it grow to this level is amazing."

'Spectacle of colour'

Lord Mayor of Belfast, Arder Carson, and other councillors helped to carry a banner calling for marriage equality as the parade moved off from Custom House Square.

Speaking ahead of the march, the mayor said he was looking forward to "another fantastic event for the city".

"It's going to be a spectacle of colour, it's going to be an expression of identity and an expression of diversity for Belfast".

Image caption The event marked the 25th anniversary of the Belfast Pride parade

Image caption Lord Mayor of Belfast, Arder Carson, said the parade was an expression of identity and diversity

The Sinn Féin councillor said marking the 25th anniversary of the first Belfast Pride parade was a "milestone" for the gay rights movement.

"It started small scale way back in the day and it's just grown, year on year, and I suppose today, being a quarter century, is of special significance for the Belfast Pride festival.

"So I dare say, we'll have a few more visitors in the city today because of that," Mr Carson added.

Image caption The parade began at Custom House Square in the city centre at noon

After voters in the Republic of Ireland supported the introduction of same sex marriage in a referendum in May, Northern Ireland is now the only part of the UK and Ireland where gay marriage has not been legalised.

The Northern Ireland Assembly has voted on the issue four times and each time it has been rejected by MLAs.

On Saturday, Christian protesters staged a demonstration against the march outside Belfast City Hall, but they were far outnumbered by supporters.

One the protesters, Ken Elliott from Portadown, said: "I suppose there'll be a lot of pressures on the legislators to make a change. But whether it changes or not, it's still wrong, the Bible is against it."

Image caption Christians staged a protest outside Belfast City Hall as the parade passed the building

A police spokesman said officers estimate that up to 6,000 people took part in this year's Pride parade but they do not have an official estimate of the thousands more who lined the city centre to watch the parade.