Stelios Haji-Ioannou, the founder of easyJet, is squaring up for a fight for control of Britain's largest no-frills airline. "Think of a number and double it," he said when asked for the share price at which he thought a bid for easyJet should go through.

The Greek Cypriot entrepreneur was speaking at the British Library yesterday, at a travel event organised by The Independent. Stelios, as he likes to be known, is still easyJet's biggest shareholder with 16.6 per cent of the equity; his family holds a further 24 per cent. But an Icelandic firm, FL Group, has built up a stake of 16.2 per cent - precipitating rumours it could bid for the whole airline.

The airline started flying from Luton to Glasgow in November 1995, and floated five years later. Many of itsinnovations - such as sellingfood and drink, and offering the lowest fares online - have been emulated by rivals.

In 2006, easyJet is likely to overtake BA in the number of passengers carried. But it has never matched the financial success of its arch-rival, Ryanair. "The evidence so far is that being ruthless and nasty actually makes money", was Stelios's view of the Irish no-frills airline. "We are nice to people, we compensate them for when we do something wrong."

Ryanair's chief executive, Michael O'Leary said: "Ryanair's average fare is £27; easyJet's average fare is £42. Others talk low fares, Ryanair delivers."

Following the terrorist attacks of 11 September 2001, easyJet and Ryanair expanded quickly, each buying up a rival along the way. Ryanair bought Buzz for what Michael O'Leary, the chief executive, called "small change". In contrast, easyJet paid £374m for Go, which began life as the no-frills offshoot of BA.

"I don't believe we overpaid," said Stelios. "We got the money back that we paid for Go more than once over with the discount we got from Airbus." In 2002, easyJet placed an order for 120 Airbus A319s, with an option for 120 more, at an undisclosed - but very low - price.

Despite such opportunism, easyJet's shareholders have had a bumpy ride; in 2004, amid intense competition and rising fuel prices, the airline had to issue a profits warning and the share price slumped below 120p. On Monday, the price broke through the 400p barrier for the first time in three years on bid rumours.

Low-cost flying is also threatened by heavier taxes, amid growing concern about environmental harm. Stelios acknowledged that "the phenomenon of the second home abroad is the creation of the low-cost airline".

The entrepreneur has started 15 other businesses, from a cruise line to a pizza-delivery company. He conceded that his easyCar venture initially "damaged the brand for a while, so we had to move away from ... charging people for the damage to the cars". He also said his initial decision only to rent out Mercedes A-class cars was "very bizarre", and said "Mercedes ripped us off".