A row has broken out between SNP politicians over a motion on gay marriage.

This week, SNP MSP John Mason tabled a motion which says no one should be “forced to be involved in” gay marriages.

Several MSPs from other parties criticised him and a fellow SNP politician has now attacked the “nasty” motion.

Pete Wishart, the MSP for Perth and North Perthshire, wrote on Twitter: “John Mason’s nasty little anti-gay marriage motion is just wrong, and really disappointed that other colleagues have signed it.”

Speaking to The Scotsman, Mr Wishart added: “I believe John’s got it totally wrong on this one. My views on this have been pretty straight forward over the years. One of the things I feel very passionate on is equality issues. I do respect that when it comes to conscience issues people have their own minds to make up, but to put a parliamentary motion was a bit disappointing.”

Mr Mason’s motion reads: “While some in society approve of same-sex sexual relationships, others do not agree with them … No person or organisation should be forced to be involved in or to approve of same-sex marriages.”

Other MSPs criticised him and accused him of misunderstanding or trying to confuse the issue.

Deputy Scottish Labour leader Johann Lamont told the Scotsman Mr Mason’s views were “bizarre”, while Green MSP Patrick Harvie, who is gay, accused him of being stuck in the “dark ages”.

In response to the motion, Scottish Liberal Democrat leader Willie Rennie submitted an amendment calling for marriage equality and praising the new SNP government for announcing a consultation on the issue.

Polls suggest growing support for marriage equality in Scotland and the Scottish youth parliament has just launched a campaign to persuade politicians to back the issue.

The new SNP government has promised a consultation on the issue.