Madrid Two Greenpeace activists flew over Spain’s oldest nuclear power plant on Tuesday in a motorised paraglider to draw attention to the alleged lack of security at the facility, the organisation said.

The activists threw smoke bombs on the roof of the building that houses the reactor of the Garona nuclear plant located near the northern city of Burgos from the paraglider, which carried a banner that read “Garona close now”.

In February Spain’s conservative government extended by five years the operating licence of Garona, which began operating in 1971.

“With this action Greenpeace reiterates that there is no economic or energetic reason that justifies the extension of Garona’s licence,” Greenpeace said in a statement, adding its stunt “highlights the lack of safety at the plant”.

Garona is owned in equal parts by Spanish power companies Iberdrola and Endesa via their joint venture Nuclenor.

Greenpeace has pressed for its closure, portraying it as a “twin sister” of the Fukushima plant in Japan that was hit by an earthquake and tsunami in March 2011, causing reactor meltdowns.

Garona had been due to close on April 1, 2013, under a decision taken by Spain’s previous Socialist government.

But lawmakers in February agreed to eliminate the pre-established lifespan limit of 40 years for the country’s six nuclear power stations as Spain tries to reduce its dependence on petroleum energy sources.

Last month Greenpeace activists in France flew a motorised paraglider inside the grounds of the Bugey nuclear power plant in the south-east of the country to expose the vulnerability of the facility.