LONDON, August 18, 2008 (AFP) - Britain's Spanish-owned airports operator BAA said Monday that it has completed a major restructuring of its debt that totals 13.3 billion pounds (16.8 billion euros, 24.8 billion dollars).

'BAA is today (Monday) pleased to announce the successful completion of the 13.3-billion-pound refinancing of its United Kingdom airports,' BAA said in a statement.

'The transaction establishes a stable, long-term, investment grade financing platform for investment in Heathrow, Gatwick and Stansted airports over the coming decades.'

BAA runs the three airports which border London, as well as Southampton airport in southern England, and Edinburgh, Glasgow and Aberdeen in Scotland.

'This is the largest financing of its kind ever completed and the fact that a landmark transaction of this size and complexity has been completed in challenging credit markets is a testament to the strength of the business and the confidence of the financial markets in BAA and its airports,' group chief executive Colin Matthews said in the statement.

The refinancing package allows the group to invest three billion pounds across the seven airports, BAA said.

This week, meanwhile, Britain's Competition Commission (CC) regulator is widely expected publish the provisional findings of a probe into the market for British airport services.

In April, the CC had said in an interim report that BAA's ownership of seven key hubs may not be in the best interests of airlines or consumers -- and indicated that it could force a sale of one or more airports.

The Financial Times reported on Saturday, without citing its sources, that rival investment groups and infrastructure funds were preparing to launch bids for airports owned by BAA.

BAA holds a 60 percent market share of all passengers passing through British airports, a figure which rises to 90 percent around London, according to Competition Commission data quoted by the business daily.

British airlines have repeatedly called for the break-up of BAA which was bought in 2006 by a consortium led by Spanish construction group Ferrovial for 10.23 billion pounds.