Berkeley said it was not aware of any information that could explain the trading, instead highlighting recent municipal elections in Retortillo, Spain, that saw the People's Party win four of the five council seats.

Berkeley is developing the Salamanca uranium project in the region.

The People's Party platform includes plans to run nuclear plants for as long as the regulator deems them safe, as well as a possible windfall tax on cheap nuclear power in exchange extending the life of the power plants.

The result of the election should be positive for Berkeley, which is the only listed uranium miner in Spain. It faced opposition to Salamanca's development last year from the ruling Socialist Workers' Party, which planned to block the last two permits required. 

Berkeley appealed in April to the Supreme Court against the nomination of new members to the nuclear safety council, including one activist campaigning against Salamanca, which would assess the project and decide whether the government should issue the final permits.

The People's Party also asked for the nomination to be suspended, with its request refused.

"The company has no other explanation as to why there has been an increase in the price and volume of trading in the securities," Berkeley said.

It assured the ASX it was in compliance with listing rules.

On the ASX, Berkeley's shares (ASX:BKY) rose 30.19% to A34c, while in London its stock (LSE:BKY) gained 28.13% during morning trade to 19.54p.