Ed Miliband has paid tribute to Labour backbencher Jim Dobbin, who has died suddenly aged 73.
The Heywood and Middleton MP is believed to have been on a trip to Poland with a parliamentary committee.
Dobbin was a microbiologist for three decades before securing the seat in 1997, and had a 6,000 majority in 2010.
The Labour leader said: "Jim's death is a sad day for parliament. He was a dedicated public servant, representing the people of Rochdale on the council and at Westminster for three decades. Working in the NHS for more than 30 years, Jim had a deep passion for helping others.
"A lifelong committed Catholic, Jim always took a lead in fostering links between the Church and the Labour Party, and his strong faith informed every aspect of his political and public life. This was recognised by Pope Benedict XVI when he made Jim a Papal knight.
"I will miss Jim's good friendship and decency. On behalf of the Labour Party, I offer our sincere condolences to his wife, Pat, and their children. We will all miss him."
Dobbin was on a Council of Europe trip to Poland when he died. His wife is believed to have been with him.
Former deputy prime minister Lord Prescott, who was part of the group visiting Poland, added his voice to the tributes.
"Jim Dobbin was part of our Council of Europe delegation that was in Poland yesterday to award the Europe Prize to the Polish city of Slupsk," he said.
"Jim was an excellent local MP, a strong believer in Europe, a proud Scot and a passionate defender of the NHS. His passing is such a tragic loss and he will be sadly missed by the Labour movement. Jim was a great comrade.
"Our thoughts are with his wife Pat and their family."
Commons Speaker John Bercow said: 'It was with great sadness that I heard of Jim Dobbin's death.
"He was a deeply principled and independent-minded parliamentarian; respected and well-liked by his colleagues, he will be greatly missed.
"My condolences go to his family. I'm sure members from across the House will hold Jim's wife, Pat, and their children in their prayers and thoughts at this time."