The Select Committee for the Environment, Transport and the Regions warned that cutting costs should not be put ahead of saving lives.
The MPs also called on the Government to undo the merger of the Coastguard Agency and Marine Safety Agency, which was completed only nine months ago.
The newly formed Maritime and Coastguard Agency (MCA) wants to close four of the 21 centres - at Liverpool, Oban in Argyllshire, Pentland in Orkney, and Tyne - and merge two others, at Lee-on-the-Solent in Hampshire and Portland in Dorset, to create a new centre.
The MCA refused to comment on the MPs' report, but a well-placed source said that modern stations were a vast improvement on the "shabby" stations of previous decades.
"There has never been a better time to sink your ship or set fire to your boat. There has never been a promise better kept than that, as technology increased, stations would be reduced but become bigger and better manned," the source commented.
In their report, the MPs said: "We are extremely worried about the closure programme, with its attendant risks that watch officers in the stations that remain might be overloaded with work, particularly in the event of a major incident, that threatened stations might be blighted and about the effect of the programme on staff."
The committee said the plan, which would lead to 78 job losses, would save only pounds 500,000 and would be inexpensive to halt. "The Coastguard is an extremely effective, and very cheap, service of which we should all be proud," the report said.
"We do not accept that now, when the number of incidents dealt with by the Coastguard is rising steeply, when the average cost of responding to each incident has fallen so sharply, and when our record compares so favourably with other countries, is the time to close maritime rescue co-ordination centres."
The MPs' report said local knowledge was "fundamental" for coastguards, helping them to respond quickly and well to incidents, thus saving lives.
"The closure programme, by requiring watch officers to cover more lengthy stretches of coastline, threatens to dilute local knowledge to such an extent that its value will be reduced, with a potentially very serious impact on the performance of the Coastguard service."
The committee said it did not believe the MCA could deliver better safety and environmental protection at sea than the two branches of the service separately. "We recommend that the two agencies should be demerged and that the Coastguard Agency and MSA be re-established," it said.
"In doing so, the agencies and the Government should remember that the best way of protecting seafarers, vessels and the general public is not necessarily the cheapest way, but the way which prevents pollution, ensures that ships do not get into difficulties in the first place, and above all saves lives."
The coastguards' workload has increased steadily. In 1987 they were involved in 5,563 incidents compared with 11,667 in 1997, a rise of 110 per cent. In 1997 they helped 16,884 people compared with 8,867 in 1987, a 90 per cent rise. Over the same period, the number of lives lost remained constant, at about 250 a year, and the cost of dealing with each incident fell.
The Public and Commercial Services Union said the report vindicated its opposition to the closure of coastguard stations. "We wholeheartedly endorse the committee's recommendation to keep them open - it is the only sensible course of action. Ministers should now halt the closures before lives are put at risk."
Until the late 1970s there were coastguard watch posts every few miles. As technology improved, station numbers fell to 28 in 1979 and 21 today.Reuse content