The chairman of cut-price carrier easyJet staged a guerrilla raid on the inaugural flight of his British Airways-run arch rival yesterday by appearing on board and offering passengers a free flight on his own airline.

In a bizarre twist to the battle between his no-frills company and BA's Go, easyJet chairman Mr Stelios Haji-Ioannou and six colleagues booked themselves onto their rival's inaugural flight wearing bright orange boiler suits for maximum attention.

To rub their point in - with Go chief Ms Barbara Cassani also on the plane - the easyJet team handed out a letter to each passenger that said "the unbelievable fare you are enjoying today is the result of a revolution led by easyJet". The letter, signed "Stelios", accused British Airways of trying to "force the existing low fare airlines out of business before they put their fares up again". "Remember, if there was no easyJet, there would be no BA-go," the letter said. "In the past, BA put competition out of business."

Mr Haji-Ioannou, whose company is sueing British Airways, went on to invite every passenger on the BA flight to a free trip this summer to Athens, Mallorca, Nice, Geneva, Amsterdam, Barcelona or Scotland.

Go is offering a price of £100 sterling ($163) for return flights from London to Rome, Milan and Copenhagen.

It is British Airways' attempt to catch up with the dynamic low-cost market, which also includes British company Debonair, Ireland's Ryanair and Virgin Express, the Belgian subsidiary of Britain's Virgin.

There are no free drinks and meals, reservation procedures are simplified and secondary airports are used.