MADRID (Reuters) - Spain's economy could expand by more than 3 percent this year, above the government's official forecast and regardless of the result of Britain's vote on leaving the European Union, acting Prime Minister Mariano Rajoy said on Wednesday.

A win for anti-austerity party Unidos Podemos (Together We Can) in the Parliamentary election on Sunday however could hurt the country's growth possibilities, he reiterated.

"I believe we'll grow, if they don't do anything stupid (in the elections), by more than 3 percent, regardless of the result of the British referendum," Rajoy said in an radio interview.

The government's official growth forecast for this year is 2.7 percent from a year earlier after 3.2 percent in 2015.

(Reporting by Paul Day and Jose Elias Rodriguez; Editing by Rodrigo de Miguel)