India-born Labour Member of Parliament Ashok Kumar, who was known as a natural fighter and community leader in his north-east England constituency of Middlesbrough South and East Cleveland, was found dead in his house on Monday.
Kumar, 53, suffered a "sudden accidental" death, his office has said.
"At this stage it is too early to say whether the death is being treated as suspicious and inquiries are ongoing," a police spokesman said.
House of Commons speaker John Bercow paid tributes to Kumar at the start of business.
"It came as a huge shock to everyone. Ashok was a fine politician who served his constituency and his constituents with diligence and unswerving commitment," a spokesman for Kumar's office said.
"He was a natural fighter and a community leader. He first won his seat in 1991 in a by-election, only to narrowly lose it in the 1992 general election. Undaunted, he stood again and in 1997 regained the seat and successful defended it in following contests," he added.
Announcing the news to the House of Commons on Monday afternoon, Bercow said, "Ashok was a most assiduous Member, much respected by the House and by professional background a very fine chemical engineer.
"I am sure members on all sides of the House will join me in mourning the loss of a colleague and extending our sympathy to the honourable member's family and friends." In the House of Commons, Kumar worked with Environment Secretary Hilary Benn, who said he was "deeply shocked and saddened."
"It is very hard to believe that Ashok is no longer with us Ashok was a pioneer, a doughty fighter for his constituents and a Labour man through and through who cared deeply for others," he said.
He was also fearless in pursuit of what he saw as right. I came to value his friendship, his loyalty and his sense of fun over the many years we worked together, Benn added.
