Romania's president has nominated the country's intelligence service chief as prime minister hours after Emil Bloc resigned amid austerity protests.

"The ruling coalition agreed to appoint Mihai Razvan Ungureanu as prime minister designate," President Traian Basescu said in a statement.

The nomination now requires approval by Romania's parliament.

Mr Boc said he was stepping down to "defuse political and social tension" in the face of three weeks of protests.

Speaking after a cabinet meeting, he said he had given up the government's mandate as "it is the moment for important political decisions".

Although Romania's economy grew last year, the government has been hit by widespread demonstrations.

Mr Boc has imposed a 25% cut in public sector wages and a freeze on pensions.

Sales tax was also increased to 24%, in a country seen as Europe's second poorest.