Bulgaria's President Rumen Radev on Wednesday vetoed legal changes that would allow the government to seize control of Lukoil's Burgas oil refinery and sell it to protect the plant from the impact of U.S. sanctions.

Radev returned the legislation to parliament for further discussion, saying the changes failed to provide protection against future financial claims against the state, violated Bulgaria's constitution and posed a risk to public finances.

Parliament adopted the legal changes last Friday, expanding the powers of a special commercial manager appointed by the government who will be able to oversee the continued operation of Lukoil's refinery in Bulgaria beyond November 21, when the U.S. sanctions are due to take effect, and to sell the company.

"The scope of application of the law has been expanded unjustifiably and dangerously," Radev said in a statement, adding that guarantees designed to reduce the risk of future claims against the state had been scrapped without reason.

In Bulgaria, however, the president is a largely ceremonial figure and parliament can override his veto.

The U.S. and Britain last month imposed sanctions on Lukoil (LKOH.MM), opens new tab and Rosneft (ROSN.MM), opens new tab, Russia's two biggest oil companies, over Moscow's war in Ukraine, threatening their operations that still sprawl across Europe.