Earlier this week, Go announced that it will be offering pounds 100 return fares when its Stansted to Rome, Milan and Copenhagen services start later in the spring.
Yesterday, KLM said that it was bringing its Stansted to Milan return air fare down from pounds 104 to pounds 100 to match Go's offer.
KLM is also reducing its one-way Stansted-Milan fare from pounds 79 to pounds 50. In addition, another "no-frills" carrier - Debonair - said that it was introducing pounds 99 return fares on its Luton to Rome service until 9 June.
After that, and until October, the lowest Debonair return fare on the route will be pounds 109 - a pounds 10 reduction on the pre-April price. The airline also intends to introduce a second daily service to Rome from the end of this month to match the Go frequency.
Go's Rome services start on 22 May, with Milan flights beginning on 23 May and Copenhagen starting on 5 June. There are two weekday flights a day to each destination, using 148-seater Boeing 737s.
Meanwhile, Air France has increased its Heathrow to Paris weekday frequency from 11 to 14 flights and has added an extra, fourth, daily flight on the Manchester to Paris service.