Plans to introduce same-sex marriage in Scotland could open the door to polygamy, a senior Labour politician has warned.

Labour’s Elaine Smith, deputy presiding officer in the Scottish Parliament, suggested the SNP government’s proposals should be put on hold until the impact of the changes south of the Border can be judged, the Scotsman reports.

Those who speak out in opposition are subjected to “vilification and bigotry”, Ms Smith said in a lengthy submission to Holyrood’s equal opportunities committee which is taking evidence into the new laws.

The first gay marriages in Scotland will be held in 2015 if the Marriage and Civil Partnership Bill is passed.

The changes will redefine the nature of marriage, the Labour MSP said, which could “cause problems for society overall”.

She pointed to “progression” in the Netherlands, which was among the first countries in the EU to introduce gay marriage in 2001 and now has civil union arrangements for three or more people which has been dubbed “polygamy in all but name”.

Ms Smith stated: “Whilst the government has said that it has no intention of allowing polygamous marriages as part of this legislation which changes the essential nature of marriage, it has not explained in any detail and with research analysis its reasons for taking that position.

“Further, if the government is sincere about its support for ‘equal love’ then it appears to have a contradiction on its hands.”

There is “no logical reason” for discriminating against more than two people getting married if the redefinition of marriage is driven by love, Ms Smith adds.

The claims were dismissed by the Equality Network which has campaigned for the changes.

“It is nonsense to suggest that this bill will lead to polygamous marriages in Scotland, and it is quite wrong to suggest that the campaign for equal marriage has anything to do with polygamy,” director Tim Hopkins said yesterday.

In August, writer Laurie Penny said in the Guardian that introducing polygamy in the wake of same-sex marriage might not be such a bad idea.

Ms Penny said she “can’t be the only one” who wonders if there are some positives to multi-partner marriage.

And commenting on a recent BBC radio programme that predicted monogamy would lose its “moral monopoly” within 10 years, Miss Penny said: “Bring it on”.

Meanwhile actress Emma Thompson has said she thinks monogamy is an ‘odd state’ and that the ‘disbelief and horror’ of infidelity is unrealistic.

She said: ‘I do think that monogamy is an odd state, and actually I think it’s an odd state for women.

‘I think that we’re locked into certain ideas and certain romantic ideals that have shaped our thinking about relationships for some time.

‘And I do sometimes wonder about whether there are alternatives, and about whether our fury and rage and disbelief and horror about infidelity is quite realistic.