Hungary's prime minister Viktor Orbán has said European leaders need to encourage Christian couples to have more children, rather than relying on migration to stop populations shrinking.

Mr Orbán was speaking at a "demographic summit" in Budapest attended by Czech and Serbian leaders and the former Australian premier Tony Abbott.

The nationalist leader, whose anti-immigration views have put him at odds with European Union leaders, said: "If we accept migration as a solution [to falling birthrates] then we are contributing to population replacement."

The term "population replacement" is associated with the far-Right theory of the "great replacement," which argues that the white, Christian population in Europe is being "replaced" by a population of non-white, Muslim refugees and migrants.

According to Hungary's 2011 census, less than 0.1 percent of the population said they were Muslim.

Mr Orbán also said environmental arguments against having fewer children – a view recently put forward by the UK's Prince Harry and his wife Meghan Markle, the Duchess of Sussex – was "brainless" and "against nature."

His government has brought in financial incentives for people to have more children, including a lifetime tax break for women who have four or more.

The country's aim is to boost the birth rate to 2.1  children per woman by the year 2030. The figure in 2016 was 1.45.

Serbian President Aleksandar Vucic said his country was ready to cooperate with Hungary and the other Central European countries in tackling their demographic situation.

Former Australian premier Tony Abbott praised Mr Orban's leadership on the issue.

Mr Orban's anti-immigration policies have been criticized by the European Union as it seeks to manage the pressures of refugees and other migrants moving to the continent.

In a report in May, Dunja Mijatovic, commissioner for human rights at watchdog the Council of Europe, accused Hungary's government of using anti-migrant rhetoric that fuels "xenophobic attitudes, fear and hatred."