Calvin Harris reportedly dumped Rita Ora on Twitter.

The 'Summer' hitmaker - who has been dating the singer for over a year - took to the social media site last week to announce their relationship was over while Rita thought they had decided to try to make it work.

A source close to Calvin told The Sun newspaper: ''Rita was left embarrassed when he tweeted that it was all over.

''She didn't think he was goit to make the announcement, so she was shocked.''

Calvin's comment on Twitter read: ''To address speculation - myself and Rita ended our relationship some time ago. She is a beautiful, talented woman & I wish her all the best. (sic)''

The couple were reported to have split in January this year after a huge row, but despite attempting to make another go of their relationship, their hectic schedules meant that they rarely saw each other.

Despite being a superstar DJ, Calvin is also more camera shy than Rita, 23, who enjoys being photographed with other celebrities.

The source added: ''It was Calvin's decision to end the relationship. They had been arguing for months and had grown apart ... Calvin likes more privacy than Rita and he hated the extra attention that came with being her boyfriend.''