The twice-daily Heathrow service is due to start on 26 March

Rival airline Flybe complained to the Jersey competition watchdog and the UK Office of Fair Trading that the subsidy could distort the airline market.

But Deputy Alan Maclean, who has responsibility for the airport, said commercial sensitivities mean the amount will stay confidential.

Bmi's Heathrow service is due to begin on 26 March.

'Lost market'

The island has been without a link to the Heathrow hub since British Airways (BA) pulled out in October 2000.

In January, bmi received an undisclosed sum to set up a twice-daily service from Jersey to London Heathrow.

Deputy Maclean said the Jersey Competition Regulatory Authority had been consulted before the subsidy for bmi was agreed.

He said the deal was considered to be in the best interests of Jersey and would hopefully help recapture the "lost market" of about 45,000 inbound passengers to the island, lost when BA withdrew.