"Faced with an increasingly repressive political and legal environment in Hungary, the Open Society Foundations are moving their Budapest-based worldwide operations and staff to the German capital, Berlin", the group said in a statement.
Orban, an avowed nationalist and critic of Western Europe's embrace of refugees, blamed Soros for much of the country's economic woes ahead of his recent reelection.
Patrick Gaspard, president of the Open Society Foundations, said on Tuesday that Budapest had "denigrated and misrepresented" the organization's work and repressed civil society "for the sake of political gain".
"We are going to reaffirm those elements of our sovereignty which are under attack", Orban spokesman Zoltan Kovacs said in a statement.
The legislation is branded as "Stop Soros" and the Hungarian government warned on Monday that legislative measures may yet become tighter.More news: Newcastle United smash listless Chelsea, finish 10th
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The Open Society Foundation (OSF) backed by Hungarian-born USA billionaire George Soros is moving from Budapest to Berlin, the German public broadcaster DW reported on Tuesday.
The building that houses the Budapest offices of the Open Society Foundations in Budapest, Hungary.
Government pressure shows no sign of easing, however: Mr Orban said recently that he would not "shed crocodile tears" over the OSF, and he backed a pro-government magazine's publication of a list of more than 200 Hungarian NGO staff, academics and journalists whom it called "Soros mercenaries". The Central European University, a graduate school started by USA billionaire George Soros, said yesterday it would stay in Hungary's capital despite a decision by its founder's foundation to leave. It would also impose a 25-percent tax on foreign donations to NGOs that back migration.
OSF said it would continue to support civil society groups in Hungary, but beneficiaries of its grants such as the Hungarian Helsinki Committee expressed concern that they too might come under heavier political and legal pressure.
Central European University in Budapest, another institution that was founded and funded by Soros, remains in a state of limbo.
Also, foreign citizens and Hungarian nationals who support illegal immigration could be subject to a restraining order which would keep them away from the border.