LONDON (AP) _ Four directors of the London Futures and Options Exchange resigned following an investigation into irregularities, the exchange announced Tuesday.

An investigation by the Securities and Futures Authority found the directors had engaged in ''non-commercial'' transactions to give the appearance of activity in the exchange's property futures market.

They were identified as Graham Cooper, director of Marshall, French and Lucas Ltd.; Richard Reinert, managing director of Refco Overseas Ltd.; Michael Overlander, managing director of Sucden (UK) Ltd. and John Brackley, director of Prudential-Bache.

The Securities and Futures Authority said in a statement it had also fined the four firms involved and Hambros Bank Ltd. a total of 340,000 pounds, or $619,000.

It said: ''This practice (of non-commercial trades) is wholly unacceptable and is regarded by the authority as a serious failure of compliance with high standards of market conduct.''

The Futures and Options Exchange's property futures market, which opened in April, was closed in October following the discovery of possible irregularities.

The Securities and Futures Authority said its subsequent investigation showed only 7 percent of the business recorded in property futures - contracts to buy and sell at future dates - were genuine deals.

It said the exchange paid Marshall, French and Lucas Ltd. $300,400 to cover any losses incurred in the market.

The former chairman of the exchange, Saxon Tate, and its chief executive Mark Blundell resigned over the affair earlier this year.