Máté Kocsis, the Fidez party's parliamentary group leader, said the ruling party will "use every means to protect Hungary’s sovereignty".

In a post on Facebook, Kocsis said that in recent years, "foreign powers and speculators" had been interfering in Hungary’s internal affairs on an increasingly broader scale, adding that they had also conducted "a Europe-wide smear campaign" against the country.

He said this had been done through "fake civil organisations, bought politicians and self-proclaimed independent media". The financiers in question, he added, had aimed to carry out their influence operations to enforce their own financial, economic, ideological and political interests.

To curb such operations, the government is introducing several new regulations modelled after what has been done in the United States, Kocsis said, adding that one such regulation will also be enshrined in the constitution.

The constitutional amendment proposal posted by Kocsis reads: "A Hungarian citizen who is also a citizen of another state may be expelled from the territory of Hungary under conditions specified by law if their activities endanger the national sovereignty, public order, territorial integrity or security of Hungary."