Eurotunnel had planned to start its shuttle service for lorries on 7 March but the equipment is not yet ready to be tested by the Channel Tunnel Safety Authority for obtaining a certificate.
This service is now unlikely to start before April with Le Shuttle road freight services 'building up during the weeks prior to 6 May'.
The delay will have a knock- on effect on the passenger shuttle which had been expected to start on 8 May, two days after the tunnel's formal opening by the Queen and President Mitterrand.
A statement by Eurotunnel said that although the 'structure of the system is sound and no fundamental problem has emerged', several commissioning tests have to be repeated because first attempts had failed. All equipment on the 50km long tunnel has had to undergo a series of stringent tests to ensure safety. There have also been additional delays in getting the locomotives ready for operation.
Eurotunnel is offering refunds to people who have bought tickets intending to travel in May.
Eurotunnel is unwilling to give a new date for when services will start because 'we don't want there to be any more delays'. However, the latest setback is a further embarrassment to the troubled company which is due to seek another pounds 1bn in financing in the spring. This will bring the total cost to pounds 10bn, twice the original estimate needed to tide it over while business builds up in the early years.
Richard Hannah, of UBS Phillips & Drew, said the delay would cost Eurotunnel up to pounds 50m for each summer month which is lost. 'This is quite serious and will have a knock-on effect for many years. It will make it more difficult when Eurotunnel seeks its extra financing.'
The tunnel was originally supposed to open in May last year but stringent safety requirements, hold-ups in delivery of rolling stock and a lengthy dispute with the tunnel's contractors, Transmanche Link, all contributed to delays.
Through freight trains, run by the BR subsidiary Railfreight Distribution, had also been expected to start on 7 March and a spokesman said: 'We were ready to start and are deeply disappointed. We are seeking an urgent meeting with Eurotunnel.'
Eurostar passenger trains between London, Paris and Brussels are to be launched later in the summer but no firm date has yet been set because of concern over deliveries of the rolling stock.