Labour minister Lord Sainsbury has been cleared of breaching the ministerial code after failing to disclose a £2m party loan, Downing Street has said.
Lord Sainsbury is believed to have donated £6.5m to party coffers
Lord Sainsbury had apologised for unintentionally misleading the public, saying he had confused the loan with a £2m declared donation he had made.
He was cleared in an inquiry carried out by his permanent secretary, according to Downing Street.
But some opposition MPs are demanding an independent investigation.
They want an inquiry by the newly-appointed independent adviser on ministerial interest John Bourne.
Supermarket millionaire Lord Sainsbury, a minister in the Department of Trade and Industry, is believed to have donated £6.5m to the party coffers since 2002.
He is the latest figure to become embroiled in the loans row after his admission over the £2m loan, which was made shortly before the last election.
On Friday, it was revealed that the Conservative Party owes £16m to 13 wealthy supporters who helped bankroll its election campaign.
But the identity of backers it has repaid £5m - including a number of foreign nationals - will remain secret, which prompted criticism from Labour.
Labour published its own list of lenders - totalling nearly £14m - nearly two weeks ago, following claims - denied by Tony Blair - it was selling peerages.