David Cairns, the Labour MP for Inverclyde, has died at the age of 44 after a short illness.
The former Scotland minister had been suffering from acute pancreatitis since March. He died in hospital in London last night.
A Labour spokesman said: “David’s untimely death is a huge loss to parliament and politics in this country.”
A further statement from the party said: “It is with great regret that we have to announce that David Cairns, member of parliament for Inverclyde, passed away at 23.00 last night at the Royal Free, London.
“David had been suffering from acute pancreatitis after he was admitted as an emergency patient eight weeks ago.
“Our thoughts are with his partner Dermot, his father John and his brother Billy and all his many friends and family.”
Mr Cairns was a Catholic priest before turning to politics. After working as a researcher for MP Siobhain McDonagh and as a Labour councillor, he was elected as MP for Inverclyde in 2001.
He was Scottish minister between 2007 and 2008 but resigned in 2008 over Gordon Brown’s leadership.
Mr Cairns was chair of the All Parliamentary Group on HIV and AIDS and was also a patron of LGBT Labour, as well as being the chairman of Labour Friends of Israel.
National AIDS Trust called him a “visionary and inspirational leader” of the parliament group, while LGBT Labour, who called him a “very good friend”, said his death was a sad loss.
James Asser, the co-chair of LGBT Labour, said: “Everyone at LGBT Labour is very upset and shocked to hear of the death of David. He had been a great friend and champion of LGBT Labour and on issues of equality within parliament and the Labour Party.
“He was doing great work chairing the All Party Parliamentary group on HIV and AIDS and he was also outspoken against homophobia abroad.”
Fellow MPs also paid tribute to Mr Cairns. Labour MP Tom Harris wrote that he was a “gifted and popular MP with a political instinct that was second to none”, and called him “one of my closest friends”.