Hungary's domineering prime minister, Viktor Orbán, is coming under mounting European pressure to shelve changes to the constitution planned for next week which are seen as an assault on democratic rights and liberties and boosting his executive power.

In a statement reflecting deepseated anxiety at the direction Orbán is taking Hungary, Germany and three other EU countries called for Brussels to be given new powers allowing it to freeze EU budget funds to a member state in breach of Europe's "fundamental values".

Europe's human rights watchdog in Strasbourg, the Council of Europe (not an EU body), also called on Orbán to delay the constitutional changes until its experts had had a chance to scrutinise them.