The party's consumer affairs spokesman, Nigel Griffiths, said on Radio Five Live that present compensation rights over changes in charter flight times were inadequate.
He said Britain's tour operators were taking advantage of lax regulations to change flight times by 11 hours without compensation.
"I have heard reports that some tour operators are deliberately advertising attractive departure times without having available airport slots, then switching them to more anti- social but cheaper timings and pocketing the pounds 5 or pounds 10 savings."
He said that unless the industry reached a voluntary agreement before the election, an incoming Labour government would add brochure small print to the Unfair Contract Terms Act.
The call has met with a mixed response from Britain's biggest tour operators. Martin Brackenbury, a director of the Thomson Travel Group, Britain's largest, said: "There has to be an acceptance that there will be changes because the summer brochure launch pre-dates the scheduling meeting each November when precise flight timings are decided."
But Steve Endacott, sales director for Airtours - Thomson's nearest rival - said such a move would benefit "vertically integrated" companies such as his: "We have our own aircraft and rights to popular slots, so vertically integrated tour operators are well placed to meet tighter restrictions."
A meeting of the Association of British Travel Agents was told that British tourists were 30 per cent more likely to be dissatisfied with their package holidays than they were two years ago. In a Mori poll commissioned by ABTA, one in 11 tourists was unhappy with his or her holiday. When travellers were asked who they would trust to give impartial advice about a destination, half said travel agents, one in five believed tour operators and brochures but none said they would trust an MP.
The major high street travel agencies were accused of offering biased advice and "bogus discounts". Allowing big holiday companies to have their own individual travel agencies was "at best unethical and at worst illegal", said David Speakman, head of the computer-based travel agency Travel Counsellors. "How dare these big companies pretend to be unbiased. They have done tremendous damage to the independent travel agents."
Mr Speakman's appeal on behalf of the independent operators was echoed by Graham Simpson, chief of the Simply Travel company. He told delegates that the major tour operators dealt with "price and gimmicks" while the big travel agents offered "lack of personal service, lack of flexibility and a lack of knowledge".
Tony Bennett, of Going Places, told the conference the UK's five largest tour operators had lost 1 in 12 customers to smaller holiday companies over the past year.
Going Places is the travel agency chain of Airtours, and Mr Bennett was making the case that such vertically integrated travel firms were not dominating the market and reducing consumer choice.
The Office of Fair Trading has been investigating the travel industry for more than a year, but has yet to publish its findings.Reuse content