Hungarian nationalist Prime Minister Viktor Orban underscored family values and slammed the LGBTQ and gender "lobby" on Thursday at a biennial demographic summit attended by Western conservative leaders in Budapest that cements Hungary's reputation as a bastion of conservatism in the European Union.

In power since 2010, Orban has styled himself as an "illiberal" defender of "Christian Europe" and frequently clashes with Brussels over his anti-migration and anti-LGBTQ policies.

First held in 2015, the so-called Budapest Demographic Summit takes place every two years to rail against migration and urge Christian couples to have more children.

Among the first speakers at the two-day forum was former US vice president Mike Pence, who served under Donald Trump.

Pence urged western nations "to renew and preserve our families on which our civilisations have been built".

"Strong families make strong communities and strong communities make strong nations," he said, calling on governments to "put families first".

Praising Orban for introducing tax exemptions for mothers of four or more, Pence blasted China for "decades of abuses in the name of population control" under its one-child policy.

Orban, in turn, said "Hungary must defend itself because the western left-wing is attacking".

"It is trying to relativise the notion of family, its tools for doing so are gender ideology and the LGBTQ lobby, which are attacking our children," he told the forum, also attended by the heads of state of the Czech Republic, Slovenia and Serbia.

Tensions between Hungary and its EU partners boiled over in June over a controversial law adopted by the Hungarian parliament banning the "promotion" of homosexuality to minors.

Former US vice president Mike Pence and other conservative leaders are expected to attend the so-called Budapest Demographic Summit Former US vice president Mike Pence and other conservative leaders are expected to attend the so-called Budapest Demographic Summit Photo: GETTY IMAGES NORTH AMERICA / POOL

Other speakers at the forum include French far-right pundit Eric Zemmour, who is thought to be eyeing a run for the French presidency. Polish Prime Minister Mateusz Morawiecki was expected to attend but cancelled.

"I find that Viktor Orban has understood the evolution of the world... and defends the identity of his country and therefore that of Europe," Zemmour told CNews channel -- derided by critics as a "French Fox News" -- on Tuesday.

At the last forum in 2019, Orban told international politicians, religious figures and diplomats that migration was contributing to "population displacement", using a loaded term used in extreme-right wing circles.

Gabor Gyori of Budapest-based think tank Policy Solutions said Orban welcomed "with open arms" politicians and other influencers who were becoming increasingly right-wing and could "no longer find allies within the European conservative mainstream".

Last month, conservative US television host Tucker Carlson -- one of the Fox network's most popular commentators -- broadcast a week from Hungary, lavishing praise on Orban.

In an interview with Carlson, Orban warned against "interference" in next year's parliamentary elections, which are expected to be a tight race and could see his ouster.

"Obviously the international left will do everything that they can do, probably even more, to change the government here in Hungary," he said.

The 58-year-old Hungarian's anti-immigration policies, such as building border fences, also earned him praise from Trump who Orban called "a great friend of Hungary".