One of Britain’s most senior Roman Catholics has caused outrage by suggesting an MP and former Merton councillor died because he was gay.

The Bishop of Paisley, Philip Tartaglia, said society had kept “very quiet” about the death of David Cains, a former minister in the Labour Government and councillor for Longthornton ward until 2002.

Mr Cairns, a former Catholic priest himself, died aged 44 in May 2011 after being taken ill with acute pancreatitis in March, prompting many heart-felt tributes from former council colleagues.

At a conference on religious freedom at Oxford University earlier this year, Bishop Tartaglia said: "If what I have heard is true about the relationship between the physical and mental health of gay men, then society is being very quiet about it."

He went on to say: "Obviously he [Mr Cains] could have had a disease that would have killed anybody. But you seem to hear so many stories about this kind of thing, but society won’t address it."

Mr Cairns’ long-term partner, Dermot Kehoe accused the Bishop of delivering a hate speech.

He said on Twitter: “Tartaglia’s comments are hate speech. He has position of moral leadership and should not speak from ignorance of the facts... Distressing and painful.”

Mr Kehoe also told BBC Radio Scotland's Good Morning Scotland programme that the archbishop-elect "implied or stated that David's death was due in some way to his homosexuality and being gay".

Mr Cairns served as a Merton councillor for Longthornton ward, between 1998 and 2002, and as a research assistant to Mitcham and Morden MP Siobhain McDonagh.

Ms McDonagh said: “David Cairns was my best friend in politics, and like him I am a practising Catholic who takes my faith extremely seriously.

“I don’t care that Bishop Tartaglia is against homosexuality or gay marriage.

“Views like his are not only offensive and disrespectful to David’s family and friends, they also make the Catholic Church look ignorant and painfully out of date.

“He is wilfully ill-informed about medical facts and statements like these should not and do not speak for the Catholic Church.”

He remained a close ally of Ms McDonagh after being elected to Parliament himself in 2001 and achieving a high-ranking post as Minister of State for Scotland in 2007 in Gordon Brown's Government.

Indeed he would not have been an MP if were not for Ms McDonagh introducing a bill in 1999 to overturn a 200-year law which banned Catholic priests being elected to Parliament - leading to the House of Commons Removal of Clergy Disqualification) Act 2001.

The Labour party’s leader, Ed Miliband, said the comments had caused hurt, while shadow home secretary Yvette Cooper tweeted the comments were “deeply wrong, shocking and distressing. Hope he will now withdraw.”

But a spokesman for Bishop Tartaglia said: "Responding to a question from an audience member, following a lecture some months ago, Bishop Tartaglia agreed that the health risks of same-sex behaviour were largely unreported.

“He mentioned the premature death of a young, high-profile gay MP in this context. There was no intention to cause offence and he regrets that anyone may have been upset.

“The church will always be willing to offer pastoral care to those in need and in the case of the MP concerned, his funeral was conducted in the Catholic Church and pastoral support offered to his family and friends."