Image copyright Getty Images Image caption Adele's current tour has received rave reviews

Pop star Adele has announced she will headline the Pyramid Stage at this year's Glastonbury Festival.

She revealed the news live on stage at London's O2, where she is in the middle of a six-night residency.

"Who's going to Glastonbury this year?" she asked. "See you there. I'll be there. I'll be headlining on the Saturday night this year."

"I've had to keep that secret for years!" the star added. Glastonbury later confirmed the news on Twitter.

Adele now joins Muse and Coldplay at the top of the bill when the festival takes place in June.

"What a great honour it is to have the wonderful Adele confirmed for this year's Saturday night headline spot!" said festival organiser Emily Eavis.

Adele's latest album, 25, has sold more than 19 million copies worldwide, and is currently number one in the UK albums chart.

Earlier this week, the singer teased fans in Manchester that she would "see them at Glastonbury" even she didn't perform.

"I'll be dressed as Elsa and my kid will be Olaf," she said, referring to characters from the Disney film Frozen.

Last November, Adele told Beats 1 radio that she had been put off playing the festival after watching Kanye West's headline set in 2015.

"I wasn't anywhere near the stage and it was the biggest crowd I'd ever seen," she told Zane Lowe.

"I froze with fear, I just thought: 'I don't know if I can do that.'"

'Amazing'

Online reaction to Adele's booking has largely been positive.

"Adele wouldn't be my choice of headliner, but I'll bet she will be amazing," wrote Dave Gray on Twitter.

"If you don't think Adele is the best possible booking Glastonbury could make, other than Led Zeppelin, you're mad," added Haydn.

Beth Howard said she couldn't "wait to be crying my eyes out to Adele at Glastonbury."

But Hally Golightly was less positive, writing: "Adele and Coldplay headlining Glastonbury, so you can take your Mum I guess."

This year's Glastonbury festival takes place in Somerset from 22 to 26 June.

Jeff Lynne's ELO have been announced for the Sunday afternoon "legends" lot, which in recent years has been filled by Dolly Parton, Lionel Richie and Kenny Rogers.

PJ Harvey and Jess Glynne are the only other confirmed acts on the bill. The festival traditionally waits until the final tranche of tickets have been sold, following the spring resale, before revealing its full line-up.