BBC News - Hungary defies critics over change to constitution
Fidesz argues the changes are necessary to make a clean break with the previous constitution, which was adopted in 1989 when Hungary threw off communist rule.
Mr Orban had been under pressure at least to postpone Monday's vote until experts from the Council of Europe - Europe's main human rights watchdog - could examine the amendment, our correspondent says.
German MEP Alexander Lambsdorff urged the European Commission to investigate a possible "systematic violation of European values" by the Hungarian government ahead of the vote, the newspaper Der Tagesspiegel reports.
In a separate development, the prime minister described as "scandalous" a court decision against the government over state-imposed gas price cuts.
He said he would not accept the ruling scrapping recent 10% price cuts and would instead submit a new proposal to lower prices even further.
The government's measure is popular with many Hungarians who are struggling to pay their bills, but energy companies have complained that they have to foot the bill.
Fidesz argues the changes are necessary to make a clean break with the previous constitution, which was adopted in 1989 when Hungary threw off communist rule.
Mr Orban had been under pressure at least to postpone Monday's vote until experts from the Council of Europe - Europe's main human rights watchdog - could examine the amendment, our correspondent says.
German MEP Alexander Lambsdorff urged the European Commission to investigate a possible "systematic violation of European values" by the Hungarian government ahead of the vote, the newspaper Der Tagesspiegel reports.
In a separate development, the prime minister described as "scandalous" a court decision against the government over state-imposed gas price cuts.
He said he would not accept the ruling scrapping recent 10% price cuts and would instead submit a new proposal to lower prices even further.
The government's measure is popular with many Hungarians who are struggling to pay their bills, but energy companies have complained that they have to foot the bill.
