WARSAW: Poland's freedom icon Lech Walesa on Thursday said the United States was "no longer the main global power" in political and moral leadership ahead of a visit by President Donald Trump.

Trump is due in Poland on Sunday for ceremonies marking 80 years since the outbreak of World War II.

"President Trump, I urge you to regain the position of world leader for the USA," Walesa said in an interview published in Thursday's edition of Poland's centrist Rzeczpospolita daily.

"The world needs the leadership of the USA. Moral and political leadership, not only economic and military leadership," added Walesa, a Nobel Peace laureate.

Walesa led the Solidarity labour movement that brought a peaceful end to communism in Poland in 1989 and became its first post-war democratically elected president in 1990.

Working as a shipyard electrician in the Baltic port city of Gdansk, he stunned the communist bloc and the world when he led a 1980 strike by 17,000 shipyard workers.

The communist regime was forced to grudgingly recognise Solidarity as the Soviet bloc's first and only independent trade union after it gained millions of followers across Poland in the wake of the Gdansk strike.

"I have a message for President Trump: The United States was for years a good empire that led the world. Today the USA is no longer the main global power," Walesa told Rzeczpospolita.

"It still has military advantage, economically you are still ahead of others, but morally and politically the USA is no longer the world leader," he added.

Shunned by Poland's controversial right-wing government, Walesa said he would not be taking part in Sunday ceremonies in Warsaw marking the WWII anniversary.

Aside from Trump, few other major leaders are expected in the Polish capital, as French President Emmanuel Macron and German Chancellor Angela Merkel are not coming, while Russian President Vladimir Putin was not invited.

According to the Polish presidency, around 40 foreign delegations are expected, half of them led by heads of state.