Malta's Prime Minister Joseph Muscat has called a snap general election for June 3, bowing to pressure over his family being embroiled in the Panama Papers scandal.

With Monday's announcement, Labour Party leader Muscat, whose 2013 election as prime minister broke a 15-year-old tenure by conservatives in Malta's government, defied opposition demands for his resignation.

He denied allegations that his wife, Michelle, owns an offshore company in Panama.

"Everybody knows about the attacks made in the past few days on me and my family. I have nothing to fear because I am clean," Muscat told a large crowd in the capital Valletta for the annual Labour Day celebrations.

Having an offshore company is not illegal but it is often associated with money-laundering schemes. An investigation has been launched, but it is unlikely to conclude before the poll.

Muscat said he would ask the president of Malta to dissolve parliament.

"My duty is not just to protect myself and my family but also to safeguard my country, and I will not tolerate a situation where jobs are lost because of uncertainty," he said.

Muscat was elected with a strong majority in 2013, but his tenure has been riddled with allegations of corruption and mystery dealings with countries such as Azerbaijan.

Anti-corruption rally

Thousands took to the streets last week to protest against corruption after an investigation revealed hidden offshore companies of Muscat's energy minister, Konrad Mizzi, and his chief of staff, Keith Schembri.

Muscat was subsequently criticised for failing to take decisive action against him and Schembri.

The prime minister has, however, delivered what he calls "an economic miracle", with the first national budget surplus in 35 years, record low unemployment and steady economic growth.

Last month, Malta's left-of-centre government survived a parliamentary no-confidence vote over the Panama Papers scandal.

Following that endorsement Muscat had said it "gives us the energy to continue to work hard and achieve results".

The Panama Papers affair involved a massive data leak from the Mossack Fonseca law firm that revealed secretive offshore entities used by many of the world's wealthy to stash assets and in some cases evade taxes and launder money.