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LONDON, Oct 25 (Reuters) - A committee of senior British government ministers chaired by Prime Minister Theresa May on Tuesday backed expanding Heathrow Airport, a BBC reporter said, citing a source.

Heathrow, Europe's busiest airport, is battling with its smaller rival Gatwick for the right to expand, after successive governments failed to make a decision on a new runway due to environmental and political protests.

The government is due to make an announcement to parliament at 1130 GMT about which option it has decided to back.

"Source tells me Heathrow did get the nod in committee this morning," BBC Political Editor Laura Kuenssberg said on Twitter.

Kuenssberg did not specify which of the two Heathrow options the government had backed - building a new runway or expanding one of its existing ones.

The project is likely to face legal challenges and a final vote by lawmakers in a year's time, meaning a new runway could only open by 2025 at the earliest.

According to a three-year study by an independent Airports Commission, a new runway at Heathrow would create 70,000 new jobs by 2050 and increase gross domestic product by between 0.65 and 0.75 percent by 2050, representing a 147 billion pound ($180 billion) boost to the economy over 60 years.

May's office did not have an immediate comment on the report.

($1 = 0.8177 pounds)

(Reporting by Kylie MacLellan and William James; editing by Kate Holton) ((kylie.maclellan@thomsonreuters.com; +44 207 542 0401; Reuters Messaging: kylie.maclellan.thomsonreuters.com@reuters.net))