The BBC has been criticised after it was ruled that Top Gear's Jeremy Clarkson "deliberately" used a racist term to describe an Asian man during the programme's Burma special.

Media regulator Ofcom ruled that Clarkson's use of the word "slope" during the BBC 2 programme was offensive and in breach of broadcasting standards.

During the programme broadcast in March, Clarkson and co-hosts Richard Hammond and James May were set a challenge to build a bridge over the River Kwai in Thailand.

After completing the bridge, the three stood at one side as an Asian man walked across it. Clarkson says: "That is a proud moment, but there's a slope on it" to which Hammond replied: "You're right, it's definitely higher on that side."

Ofcom has ruled that the BBC made no attempt either during filming or post-production to check if the derogatory word – which was scripted in advance – would have been offensive to viewers.

An Ofcom spokesperson said: "After a thorough investigation, Ofcom has found the BBC breached broadcasting rules by including an offensive racial term in Top Gear, which was not justified by context.

"Jeremy Clarkson used the word 'slope' to refer both to an Asian man crossing a bridge, and the incline of the bridge. This was scripted in advance.

"The BBC failed to take the opportunity, either during filming or post-production, to check whether the word had the potential to offend viewers."

They added: "Various nationalities have, at some point, been the subject of the presenters' mockery during the history of this long-running programme. The regular audience for this programme adjusts its expectations accordingly.

"In our view, however, in this case Jeremy Clarkson deliberately employed the offensive word to refer to the Asian person crossing the bridge as well as the camber of the bridge."

A BBC spokesperson responded: "We dealt with this matter some time ago, the programme apologised at the time and explained the context, and we are now focusing on delivering another series of one of Britain's best-loved shows."

Top Gear's executive producer Andy Wilmen previously expressed "regret" over Clarkson's use of the word.

He said: "If we had known that at the time we would not have broadcast the word in this context and regret any offence caused."

The ruling arrives after Clarkson was given a "final warning" by the BBC after he admitted using the word "n****r" during an unbroadcast segment of the show.

During the footage, which was later edited out of the programme, the presenter was heard reciting the rhyme: 'Eeny, meeny, miny, mo' before appearing to mumble the line "catch a n****r by his toe".

After previously denying using the word, Clarkson said he was "mortified and horrified" after discovering he had used the racist slur and did "everything in my power" to make sure it was not transmitted.

In the past, the BBC was forced to apologise after Clarkson and the other Top Gear presenters were accused of making racist remarks about Mexicans.

During the programme broadcast in February 2011, Hammond described Mexican cars as "just going to be lazy, feckless [and] flatulent", with Clarkson insisting no one would complain about the remarks as "at the Mexican embassy the ambassador is going to be sitting there with a remote control like this [snores]".