Bulgaria's president vetoed on Saturday a parliamentary decision to relax planning restrictions on forests to boost the development of ski resorts, his press office said.

"The Forest Act amendments raise just fears for contravening the constitution and the law of the EU and for unbalanced decisions which might face us with irreparable consequences for the environment," President Rosen Plevneliev said.

Improving the possibilities for mountainous regions to develop winter tourism should not come at the expense of nature, he added.

The veto followed days of protests and road blockades by environmentalists who accused parliament of condemning forests and protected areas to destruction while favouring ski resort operators.

The changes, adopted by parliament last week, aim to relax rules on building ski runs and facilities in protected areas without the previously required change of land-use.

They would allow private companies to build in protected areas owned by the state and open farmland for uses such as the construction of ski resorts and golf courses.

The presidential veto now obliges parliament to review the regulations. Plevneliev expressed hope that this would be done through dialogue between lawmakers and environmentalists.

"This is the basis of agreement to both develop winter sports and the regions and protect and recreate the environment," he said.

The president does not have the right to make a second veto and would have to sign the changes if parliament refuses to modify them, but lawmakers had already hinted they were ready to back off some of the most controversial texts.