U2's Bono and The Edge cover ABBA's 'SOS'

The U2 singer declared himself an ABBA fan.

U2's Bono and The Edge appeared on BBC Radio 2 and paid tribute to ABBA with an instrumental cover of the Swedish band's 1975 hit 'SOS'.

"I'll tell you something, the songs are just better," Bono said of ABBA during U2's visit to BBC Radio 2's Piano Room. "You can't be empirical about everything in art, but sometimes the songs are just better," he argued.

"SOS" was a choice that perfectly suited the warm atmosphere of the Piano Room.

Bono and The Edge replaced ABBA's sunny instrumentation from the '70s with a slower acoustic beat, dressed in strings and the U2 singer's signature timbre.

"This is the great ABBA and this is a marketing ploy by U2 called 'SOS!'," Bono joked before they performed the song accompanied by members of the BBC Concert Orchestra at the BBC's Maida Vale Studios.

Speaking to host Gary Davies, the two U2 members revealed that it wasn't easy to accept their love for ABBA. In fact, when Bono first heard them as a teenager, he was reluctant to admit that he liked their songs.

"I didn't have the courage to admit it when I was 16 in the middle of punk rock," he said.

Bono - U2 - The O2 Arena

By 1992 ABBA were no longer a guilty pleasure and Bono was an avowed fan.

On a tour in Stockholm that year, U2 welcomed ABBA's Benny Andersson and Björn Ulvaeus to the stage for a cover of 'Dancing Queen'.

When Bono recalled that night, he famously told Gary Davies: "We killed it."

Bono and The Edge also performed instrumental covers of U2's 'Vertigo' and 'One' on Radio 2's Piano Room.

U2 have a busy year ahead of them. On March 17th they released their new album 'Songs Of Surrender', in which they cover 40 songs from their entire discography.

This fall, U2 will also open Las Vegas' MSG Sphere with the 'U2:UV Achtung Baby Live at the Sphere' shows.