Laws which give cohabiting couples marriage-like rights may not lead to fewer marriages, according to new research.

The claim from British researchers comes as the Irish Government looks at giving Irish cohabitees marriage-like rights.

Critics have argued that the plan could encourage fewer people to marry and therefore threaten family stability. They ask why couples would marry when the law gives them similar rights by default if they cohabit.

However academics at the universities of York and Exeter say that the introduction of financial rights for cohabiting couples in Australia made no discernible difference to rates of marriage there.

While rates of marriage have been declining gradually in Australia since the late 1970s or early 1980s, as in many other developed countries, there was no significant difference in the rate of decline before and after cohabitation law reform.

In Australia cohabitation law is a matter for the states, which brought in reforms at different times, from New South Wales in 1985 to Western Australia in 2002.

Kathleen Kiernan, professor of social policy and demography at York, and Anne Barlow, professor of family law at Exeter, who did the analysis with an Australian consultant, Rosangela Merlo, claim that the decline in marriage rates was unrelated to the cohabitation laws but was just a continuation of the general trend.

They also looked at France and the Netherlands, which have given marriage-like rights to heterosexual couples who register their unions and agree the terms of a cohabitation contract. Once again they claim there was no direct link between the reforms and declining marriage rates.