Image caption The show saw Jeremy Clarkson and his co-hosts face a series of challenges

Top Gear's Burma Special in which Jeremy Clarkson used a racial slur broke broadcasting rules, Ofcom has said.

The show featured a segment showing the hosts looking at a bridge they had built on the River Kwai as a local man walked across it.

Clarkson remarked: "That is a proud moment. But there's a slope on it."

Ofcom, who investigated after two viewers complained, said the use of the word "slope" was offensive.

After receiving complaints, Top Gear producer Andy Wilman said it was "a light-hearted wordplay joke referencing both the build quality of the bridge and the local Asian man who was crossing it".

Following Clarkson's remark, co-star Richard Hammond replied: "You're right. It's definitely higher on that side."

'Not justified'

Wilman said: "We were not aware at the time, and it has subsequently been brought to our attention, that the word 'slope' is considered by some to be offensive and although it might not be widely recognised in the UK, we appreciate that it can be considered offensive to some here and overseas, for example in Australia and the USA.

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

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."

Image caption The Burma Special saw hosts Richard Hammond, Jeremy Clarkson and James May film on the border of Myanmar (also known as Burma) and Thailand

In its representations to Ofcom, the BBC said programme makers were aware the word was "used to refer to people of Asian origin" but they considered "such use was mere slang".

It added they were not aware it had the potential to cause offence "outside the UK" and had they been aware of this offence it would not have been used.

But Ofcom ruled there was "clearly an opportunity both during filming and post-production to research the word and reach a more considered view on whether it was 'mere slang'".

Following the Ofcom ruling the BBC said: "We dealt with this matter some time ago, the programme apologised at the time and explained the context, and we are now focussing on delivering another series of one of Britain's best loved shows."

The motoring show has faced a number of controversies over the years.

In 2011 the BBC apologised after an episode in which Hammond called Mexicans "feckless [and] flatulent" and Clarkson joked they would not receive complaints because the Mexican ambassador would be asleep.

In May the corporation faced calls to fire Clarkson after he mumbled an offensive version of the nursery rhyme Eeny, Meeny, Miny, Moe in a clip that was not broadcast.

Clarkson revealed he had been given a final warning and would be sacked if he made "one more offensive remark, anywhere, at any time".