Ljubljana in Slovenia and Montpellier in France are being added to British Airways’ short-haul network from Heathrow.
Both seasonal routes will run next summer with frequency increased to Nantes, Olbia and Valencia.
Slovenia’s capital will be served twice a week on Mondays and Fridays from July 15 until September 2 with fares starting at £63 one-way.
Montpellier gains four flights a week on Mondays, Thursdays, Fridays and Saturdays across the same period with fares leading in at £38 one-way.
The two new summer-only routes from Terminal 5 follow BA adding routes to Preveza and Kos in Greece and Bastia in Corsica for next summer.
The number of flights to other leisure destinations such as Marseille, Budapest, Inverness, Palermo and Malaga are also being raised.
BA network and alliances director Sean Doyle said: “We are gearing up for an exciting summer next year as we add more routes to our extensive network.
“We’re always developing our leisure offering and are committed to giving our customers even more choice of destinations at competitively low prices.
“As well as launching five new European routes in 2019, on our long haul network we’re also starting flights to Osaka, Charleston and Pittsburgh.”