It has been an intellectual spat of some savagery, so far largely confined to the refined pages of one of Britain's most respected literary magazines.

This weekend, however, it seems ever more likely that a court will have to adjudicate between the historian Niall Ferguson and writer Pankaj Mishra over Ferguson's claim that he had been accused of being a "racist".

Indeed, not since VS Naipaul and Paul Theroux fell out has there been a spat like this in the letters pages of a literary journal. A new exchange of correspondence in the current London Review of Books, triggered by Mishra's review of the Harvard professor's latest book Civilization, which Ferguson claims was "defamatory", is evidence that the row is becoming more intense.

In his letter Ferguson charges Mishra of being "in full and ignominious retreat", condemning both Mishra and the LRB for refusing to apologise.

At the heart of the controversy is Mishra's interpretation of not only Ferguson's latest book but also his body of work in general, which has sought to challenge the view that western empires were entirely negative in their impact, and argues that colonialism could have positive effects as well.

Ferguson is best known for his popular television histories, including Empire: How Britain Made the Modern World and The Ascent of Money.

"As my last letter explained, [Mishra] made a vile allegation of racism against me," says Ferguson in his latest letter to LRB. "In his response he nowhere denies that this was his allegation; nor does he deny that he intended to make it.

"He now acknowledges that I am no racist. Any decent person would make an unconditional apology and stop there. But Mishra proves incapable of doing the right thing. His mealy-mouthed acknowledgment is qualified by the offensive suggestion that I lack 'the steady convictions of racialist ideologues', to whom his original review so outrageously compared me.

"Mishra's slippery spin on his original words is that he meant to accuse me only of a 'wider pathology' of 'bow[ing] down before the conqueror of the moment, to accept the existing trend as irreversible'. Unfortunately for his reputation, this new smear is also demonstrably false."

For his part, Mishra replies: "[Ferguson] seeks to mitigate the crimes of his beloved western empires – what he calls 'ugly methods of expropriation and enslavement' – by also implicating 'non-western' empires in them...

"It says something about the political culture of our age that Ferguson has got away with this disgraced world view for as long as he has. Certainly, it now needs to be scrutinised in places other than the letters page of the LRB."

At the heart of the row is Ferguson's anger at being placed in an unflattering proximity by Mishra to American racial theorist Theodore Lothrop Stoddard, author of The Rising Tide of Color against White World-Supremacy.

Mishra, an Indian author and essayist, who has written for the Guardian, went on to accuse Ferguson of being a "homo atlanticus redux", a "retailer of emollient tales about the glorious past" whose books "are known less for their original scholarly contribution than for containing some provocative counterfactuals".

Contacted by email, Mishra declined to be interviewed and said that he wanted to "confine" his response to Ferguson to the letters pages of the LRB.

Ferguson, who is married to the Somali-Dutch writer, activist and politician Ayaan Hirsi Ali, insisted yesterday that he would secure an apology or take the matter to court. "If he won't apologise for calling me a racist, I will persecute him until he does," Ferguson said, adding that he had been made even more angry by the fact that he had been attacked in a serious and scholarly publication such as the LRB.

"The basic insinuation [I am making] is that Mishra either did not read my book properly or if he did he was reckless. I find it staggering that the LRB is standing by him. I spoke to the editor Mary-Kay Wilmers and said: 'Don't force my hand by forcing me to put it in the hands of lawyers.' All I have got back is weasel words.

"There was a time when one expected better from the literary world, to play the ball not the man. But it seems to be becoming de rigueur for mediocrities to build their fame on attacking those more successful than them."

The LRB declined to comment.