The Metro newspaper has refused to carry an advert for a comedy show – for fear of upsetting London Underground.

Musical duo Amateur Transplants wanted to promote their West End show this weekend with a reference to their caustic Underground Song, which has been a huge viral hit.

But the free newspaper, which has a deal with transport bosses to distribute at Tube stations insisted they remove all reference to the track.

The song, which has been downloaded more than 4 million times, rewrites the lyrics to the Jam’s Going Underground with the chorus: ‘London Underground! London Underground! They're all lazy fucking useless cunts, London Underground! London Underground! They're all Greedy cunts, I wanna shoot them all with a rifle!’

When they first sumbutted their ad for their show at the Vaudeville Theatre on Sunday, it had the strapline: ‘F**ked off with the Tube strkes? From the guys who brought you The London Underground Song…’

Metro refused that; so they tried ‘Pissed off’, ‘****ed off’ and then the sarcastic ‘Loving the Tube Strikes?’

However, in the version that was approved to run today, there is no reference to the song at all, and the strap reads: ‘Loving all the Tube strikes? The most politically incorrect songs anywhere in London'.

Amateur Transplants – who are doctors Adam Kay and Suman Biswas – said they were told the paper couldn’t be seen to promote any criticism of their major partner.

They said: ‘We're completely astounded. How can the Metro possibly be relied upon to cover the Tube strikes fairly or accurately when they are clearly in the pockets of Transport for London.

‘We've always sung that the drivers are "lazy fucking useless cunts”, but didn't realise this extended to the in-flight magazine.

And banning the  fully-starred word **** seems to be a dangerous precedent to set.’

And they added: ‘Tube drivers - please don't strike over this...’

John Leitch, Metro’s director of distribution and partners, said: ‘I can confirm that we are running an ad for Amateur Transplants.

'Because of the way in which Metro is distributed, i.e. free to everyone on the public transport network across the UK (not just on the Underground), we always have to consider the concerns of the broad demographic of our readership. We're proud to have readers of every age, ethnicity and outlook and occasionally we work with our advertisers to produce content reflective of that broad demographic.'

Earlier this year, Metro retained the lucrative contract to distribute newspapers at 250 Underground stations, in a deal that runs until the end of 2017. The value of the contract is not known, nor the details of any clauses.

Here is the offending song: