The exchange said it would backdate the fee cuts to 1 April, and would look again at their impact on trading at the end of the year.

Euronext is fighting off a challenge in the Netherlands market - home to Anglo-Dutch giants Unilever and Shell - from the London Stock Exchange.

Euronext trades shares listed in Paris, Brussels, Amsterdam and Lisbon.

The cut rates Euronext is offering vary depending on the size of the trader.

The firm says passive trades of fewer than 60,000 shares will get a 50% discount on order fees "to stimulate liquidity" - and bigger deals will be free.

Home turf

The price war marks the renewal of rivalry between the LSE and Euronext.

The last tussle took place in late 2001, when London-based options and futures exchange Liffe was up for sale.

In the end, it was Euronext which won the day.

Now the LSE is taking the rivalry to Euronext's home turf, saying it will offer trading in the top 50 Dutch stocks from 23 May.