Media playback is unsupported on your device Media caption Fr Ray Kelly sang a pitch-perfect version of Leonard Cohen's Hallelujah

A priest has stunned wedding guests at the end of a ceremony with a pitch-perfect version of Leonard Cohen's Hallelujah.

The video of Fr Ray Kelly's unique version of the often-covered song was filmed at the weekend and has been watched on YouTube more than 2.7 million times in the space of four days.

The parish priest of Oldcastle, County Meath, told BBC Radio Ulster's Talkback programme that the couple had no idea what was going to happen.

"Normally local people know I sing at weddings, funerals or when I'm asked, but they didn't know - the bride Leah is from Dublin and the groom Chris is from Cookstown in County Tyrone," he said.

I enjoy singing but I wouldn't want to do it full time - I love what I'm doing as a priest Fr Ray Kelly

"They were having their reception at a hotel about 10 miles away and chose our church.

"We had the rehearsal on Thursday evening and at the end I said, 'sure maybe I'll sing an aul song for you myself' - Leah grinned and said 'OK sure' but I don't think she was taking it too seriously."

'Standing ovation'

Fr Kelly changed the original lyrics to be more suitable for a wedding. It begins: "We join together here today, to help two people on their way."

The story of Hallelujah Hallelujah was first released by Leonard Cohen in 1984, but Jeff Buckley's version ten years later found a new audience for the song and it has continued to grow in popularity ever since.

It has gone on to become one of the most covered songs of all time, tackled by everyone from buskers and karaoke singers to stars like Bono and Susan Boyle.

In 2008, it had the unlikely distinction of taking the top and second spot in the UK Christmas charts, with X Factor winner Alexandra Burke claiming the number one despite a campaign by Buckley fans. Cohen's version reached number 36 in the same chart.

Cohen wrote as many as 80 verses while composing the song before editing it down. Velvet Underground musician John Cale took some of Cohen's unused lyrics for his 1991 version, which first inspired Buckley to cover the song.

The video was filmed by a company owned by County Tyrone man Patrick Rushe, who said he was amazed by the reception it has received online.

He said he was just as surprised as anyone in the church when the priest began singing the song.

"The band Sunlight who had been doing the music for the wedding had just finished singing when he put on the backing track, but people were still looking at them as they didn't know where the music was coming from - they were shaking their heads and saying it wasn't them.

"At the end of the song he got a standing ovation.

"The couple are on their way to Mexico for their honeymoon but I sent them the link and they know it has been really popular," he said.

"Chris says it's madness while Leah says her dad is freaking out, in a good way."

Fr Kelly is a trained singer who is currently working on his third album.

"I keep saying this will be my last because this year I'm 25 years a priest - I do it to make a few bob for local charities," he said.

"I enjoy singing but I wouldn't want to do it full time - I love what I'm doing as a priest.

"The way I look at it is, it's a gift one has, and if you have a gift you use it."