Although the companies did not disclose financial terms of the deal, a source told Reuters in July that Ontario Teachers could spend up to 250 million pounds ($408 million) to buy Macquarie European Infrastructure Fund's (MEIF) 50 percent stake.

Bristol Airport, which acts as a key gateway for passengers travelling to the south-west of England, reported a pretax profit of 25.8 million pounds for 2013.

Ontario Teachers, Canada's largest single-profession pension plan, originally invested in Bristol Airport in 2001 and raised its stake to 49 percent in 2009.

While Macquarie, the world's largest infrastructure asset manager, held bulk of the remaining stake, the other 1 percent belonged to Sydney Airport. Ontario Teachers acquired Sydney Airport's stake last year.

"Macquarie and Teachers have been instrumental in supporting the expansion of the Airport's route network and significantly enhanced facilities for passengers," Bristol Airport Chief Executive Robert Sinclair said in a statement on Wednesday.

Bristol Airport catered to more than 6 million customers in 2013, more than double the 2.7 million passengers that were travelling through its doors in 2001.

The deal, which is expected to close by the end of September, marks a way for Macquarie to exit the investment before its 1.5 billion euro (1.19 billion pounds) MEIF reaches the end of its life.

For Ontario Teachers, it is another step towards its aim of expanding its infrastructure holdings from $12 billion to around $18 billion (11.03 billion pounds).

Hillbrook Partners, Macquarie Capital, Altitude Aviation Advisory, Ernst and Young and Baker McKenzie advised Macquarie on the deal.

(Reporting by Esha Vaish in Bangalore; Editing by Sriraj Kalluvila and Maju Samuel)