Mr Kumar was found dead at his home on Monday
The Prime Minister has led Commons tributes to the Labour MP Ashok Kumar who was found dead at his home on Monday.
The 53-year-old, who had represented Middlesbrough South and East Cleveland since 1997, died from natural causes.
Gordon Brown said Mr Kumar would be "sorely missed" while David Cameron called him a "great representative".
Liberal Democrat leader Nick Clegg paid tribute to an "absolutely first class" MP.
At Prime Minister's Questions, Mr Brown said: "He was a tenacious campaigner, a passionate advocate for the people of Teesside and his expertise and his wise counsel will be sorely missed at all times in this House."
Conservative leader Mr Cameron said: "He was respected on all sides of the House for his hard work representing a constituency he loved and campaigning for the causes in which he believed.
"The House has lost a great representative and our thoughts should be with his friends and family at this time."
The leaders paid tribute to Mr Kumar at Prime Minister's Questions
Mr Clegg said: "He had a reputation as an absolutely first class local MP, a defender of the steel industry.
"He spoke out on the environment before it was fashionable to do so and always spoke up for fairness."
Officers were called to the MP's Middlesbrough home after his staff were unable to reach him by telephone, and raised the alarm
Born in India, Mr Kumar became MP for Langbaurgh at a 1991 by-election, but narrowly lost the seat in the 1992 general election.
He stood again in 1997, when the constituency was redrawn as Middlesbrough South and East Cleveland, and won with a 10,000-plus majority.