Protesters also lashed out at the government and the president for supporting these controversial projects.

In Bucharest, between 4,000, according to the police, and 7,000 people, according to organisers walked between the central University Square and the government building, shouting slogans against a gold mine project planned by Canadian company Gabriel resources in the village of Rosia Montana, in the heart of Transylvania.

The open-cast mine would be the biggest in Europe, according to the company.

The project has triggered fierce opposition as the mine would use an average of 12,000 tonnes of cyanide a year in a leaching process, destroy four mountains and threaten to partially damage Roman mining galleries.

The company says European environment regulations will be respected.

"We don't want cyanide", protesters, mainly young people and families, shouted.

In the evening, they organised a sit-in on one of Bucharest's main avenues, partially blocking traffic.

"We hope we can save Rosia Montana", Irina Enea, a jewellery designer who came to protest with her husband and two children, told AFP.

"We are angry because the right to a safe environment is violated and because the government adopted a draft law saying the mine is of national interest", she added.

Romania's government on Tuesday approved a draft law granting national interest status to the Canadian gold mine project.

The draft law will have to get approval from Parliament to be valid.

Protests also took place in several other Romanian cities gathering hundreds of people each.

In Barlad (north-east), more than 3,500 people gathered to protest shale gas drilling plans by US giant Chevron.

They oppose the controversial drilling technique known as hydraulic fracturing or "fracking" which involves injecting huge amounts of water, mixed with sand and chemicals, at high pressures to break up rock formations and release the gas.

"We inherited a clean land from our ancestors. Our duty is to transmit as clean (a landscape) to our children and grandchildren but if Chevron proceeds with shale gas, they will poison the land", 86-year-old Mihai Berlea said.

Chevron says it will respect "the highest standards in terms of safety and environmental protection".

"Many protesters took to the streets today not only because of environmental concerns but because they feel they have been betrayed", sociologist Mircea Kivu told AFP, recalling that rhe ruling centre left coalition was against these two projects while in opposition.