Slaughter and May and Baker & McKenzie are advising on Lufthansa's sale of British Midland International (BMI) to British Airways owner International Consolidated Airlines Group (IAG).

Bakers is acting for Lufthansa, the owner of BMI, which operates flights to Europe, the Middle East and Africa.

The Bakers team includes Duesseldorf corporate partner Soenke Becker and London corporate partner Peter Strivens as well as Frankfurt banking partner Matthias Eggert and Berlin corporate partner Hermann Ali Hinderer. UK-based partners Louise Webb (corporate), Arron Slocombe and Robert West (pensions) and Ian Jack (banking and finance) are also acting on the deal.

Meanwhile, Slaughters corporate partner David Wittmann is leading the magic circle firm's team for IAG, which owns British Airways and Iberia.

Slaughters is a longstanding adviser of British Airways, and advised the airline on its 2011 merger with Iberia, which was structured for regulatory reasons within the multinational holding company IAG. The firm declined to comment.

The deal will see Lufthansa sell its 80% stake in the UK airline to IAG. The German flag-carrier had acquired its majority stake in BMI in 2008, upping its ownership from 30% to 80% in a deal worth €400m (£345m). The 2008 deal saw Freshfields Bruckhaus Deringer act for Lufthansa and Ashurst advise BMI.

No value for the current sale has been released, although the parties involved are aiming for the transaction to be completed in the first quarter of 2012.

The deal will boost IAG's presence at Heathrow with additional take-off and landing slots giving rise to questions from competitor Virgin Atlantic, who has also made a bid for BMI, over whether the acquisition would be anti-competitive.

Without disposals, the deal would see IAG control around half of the landing slots at Heathrow, the UK's largest airport, potentially complicating regulatory clearance.

BMI has, however, announced its intention to sell its regional assets to a "UK-based investor group previously associated with the regional business". Clyde & Co is understood to be acting for the buyer.