The Sinn Féin leader has criticised the Catholic church for their intervention in the same-sex marriage referendum debate, saying this is a civil issue and not a religious one.

It comes after letters from Catholic bishops urging a No vote on Friday were read out at masses around the country yesterday.

Gerry Adams says while the bishops are entitled to their opinion, a Yes vote will not affect church marriages.

He is also appealing to voters not to use the referendum to express anger at the government.

"There are also many practising Catholics who believe strongly in equality and who will vote to grant marriage equality to their fellow citizens," he said.

"The referendum is not about the issues of adoption, surrogacy or assisted reproduction. Nothing in the referendum affects existing adoption legislation or the rights and entitlements of children."

"I would appeal, as we enter the final few days if this referendum campaign, for a calm, reasoned, respectful and above all compassionate debate. If you are not gay, the right to marriage equality will not affect you. It will merely give the same rights to all citizens."

"I would also appeal to citizens who may be tempted to use this referendum to express anger at the government to refrain from doing so. This referendum is not about Fine Gael or Labour, or Fianna Fáil for that matter, or their austerity policies. It is about the rights and entitlements of citizens," he added.