British Airways and Indian carrier Kingfisher are to start codesharing on each other's flights across India, Sri Lanka, the UK and continental Europe.
The flights will go on sale from 7 September for travel from 15 September.
Kingfisher is due to join Oneworld with BA acting a sponsor in 2011.
The codeshare is on 11 domestic Indian routes and one route to Sri Lanka operated by Kingfisher Airlines. Kingfisher's airline code will be placed on nine British Airways routes from Heathrow to the UK regions and continental Europe.
British Airways currently flies from London Heathrow to Delhi, Mumbai, Bangalore, Hyderabad and Chennai. The Kingfisher Airlines flights which the codeshare applies to go on from four of these (omitting Hyderabad).
They are: Bangalore to Chennai, Coimbatore and Kochi; Chennai to Coimbatore and Colombo (Sri Lanka); Delhi to Bangalore and Kolkata; andMumbai to Bangalore, Chennai, Goa, Hyderabad and Kolkata.
In return, a Kingfisher Airlines code will be added to BA flights from London Heathrow to Aberdeen, Edinburgh, Glasgow, Manchester, Amsterdam, Brussels, Dusseldorf, Lisbon and Paris.
The codeshare does not apply to the flights between the UK and India. Kingfisher currently flies daily to London Heathrow from both Delhi and Mumbai, having withdrawn its Bangalore flight.
British Airways' CEO Willie Walsh said that the codeshare would allow passengers to earn miles in each carriers respective frequent flyer programmes, through-check luggage and have a smooth transfer from international to domestic services.
"Last year we proudly celebrated 80 years of flying to India and it remains our second largest destination after the US with 45 flights each week. India is one of the biggest markets in the world and could well be the biggest. We have seen steady growth in the market here and having a top quality India partner strengthens our position."
BA's regional manager South Asia, Judy Jarvis said that BA saw this as the first of a "tranche of codeshares" and said that BA would also be looking to sign further codeshares including ones from Hyderabad.
Kingfisher Airlines Commercial Director, Manoj Chacko announced that members of Kingfisher's Frequent flyer programme King Club would be able to enjoy a triple miles promotion on all international routes.
www.flykingfisher.com www.ba.com