London, July 9 (IANS) Britain's most senior Asian MP has called upon the opposition Conservative Party to sack a senior member of the upper house of parliament who mentioned the word 'nigger' during a debate Tuesday.

Lord Robert Dixon-Smith, Conservative spokesman for communities and local government at the House of Lords, described concerns over government housing legislation as 'the nigger in the woodpile'.

The phrase, used in 19th century America to describe fleeing slaves who hid in piles of firewood, later became a metaphor for a hidden fact or problem.

Keith Vaz, chairman of the parliament's select committee on home affairs, called upon Conservative Party leader David Cameron to sack Dixon-Smith, saying the remark was racist.

'I regard this remark as racist, because it's deeply offensive. It shows a lack of understanding and sensitivity to the ethnic community and seems to come from a throwback age when people used that kind of phrase as if it was normal,' the Indian-origin MP said.

'We will judge Cameron on how he responds,' he added.

Dixon-Smith apologised after a fellow-Conservative member politely suggested he rephrase his comments.

Dixon-Smith then told the House: 'I apologise, my Lords. I left my brains behind. I apologise to the House.'

He also twice apologised to the Tory leader in the House of Lords, and later said the phrase was 'common parlance when I was younger, put it that way'.

Denis MacShane, a former Europe minister and anti-racism campaigner, said: 'Cameron always condemns, but always covers up for the ugly face of a Tory Party that can't stop itself saying out loud what it seems many of them think deep down.'

A spokeswoman for Cameron said about Dixon-Smith: 'This was not an appropriate thing to say and it was absolutely right that he apologised to the House.'