Dozens of ambassadors to Warsaw on Monday called for the protection of LGBTIQ rights in Poland, whose record on the issue was found to be the worst in the EU by an international watchdog.

Gay rights have become a flashpoint issue in Poland in recent years under the governing right-wing Law and Justice (PiS) party, which campaigns against what it calls "LGBT ideology", likening the promotion of gay rights to a form of communism.

"We express our support for the efforts to raise public awareness of issues affecting the lesbian, gay, bisexual, transgender and intersex (LGBTIQ) community and other communities in Poland facing similar challenges," the open letter said.

"To shield communities in need of protection from verbal and physical abuse and hate speech, we need to jointly work on an environment of non-discrimination, tolerance and mutual acceptance," it said.

The letter was signed by diplomats from 40 countries, including the US and most of Poland's EU partners, as well as representatives from the European Commission, the United Nations refugee agency (UNHCR) and other organisations.

In December, the Council of Europe classed Poland's record for LGBTIQ rights as the worst in the EU and said leading politicians had made the situation even worse in recent years.

PiS party chief Jaroslaw Kaczynski has said gay people are a threat to the traditional family and President Andrzej Duda has equated "LGBT ideology" with communism.

With support from the government, several regions have also declared themselves free from "LGBT ideology" in Poland.