A British chess grandmaster is under fire after mocking a rival's Christianity.

Nigel Short, the only Brit ever to challenge for the world title, was forced to defend himself, according to the Telegraph, after he ridiculed Wesley So, the US champion, who has made a habit of praying before every match.

So, a committed Christian, suffered a rare defeat in his opening match of the Candidates tournament in Berlin, on Saturday, losing in 33 moves to fellow American Fabiano Caruana.

Short, an atheist, tweeted: 'Congratulations to Fabiano Caruana on the first victory in the Berlin Candidates. The Lord deserted Wesley So today. Apparently, he didn't pray fervently enough.'

He was accused by chess fans of being 'hateful' and 'classless'.

But Short hit back and said: 'Why hateful? This is a man who publicly credits all his victories to the Lord. There must be some logical explanation when he loses, mustn't there?'

He added in response to accusation he did not respect So's deeply held belief, Short added: 'It may well be a dearly held belief, but that does not mean it is either sensible or worthy of respect, does it?'

Undeterred by the criticism he tweeted on Sunday: 'The problem with praying to the Lord on Sunday is that it is his day off. Paradoxically this is the very day that he is inundated with requests. No wonder he couldn't be bothered with the scores in the #BerlinCandidates.'