The U.S. ambassador to Romania on Tuesday urged politicians to continue reforms, stop political meddling in the management of state-owned companies and create a regulatory system which fosters investment.

"Stop meddling in the management of state-owned enterprises for political gain and allow these enterprises to operate according to good business practices, so that all Romanians reap the benefits," Ambassador Hans G. Klemm said at a conference organized by the American Chamber of Commerce.

Klemm praised Romania for taking steps to reduce nepotism, and for the anti-corruption drive which has seen the prosecution of senior politicians, including Prime Minister Victor Ponta whose trial began in September.

The ambassador did not cite any cases of meddling "for political gain." But among hundreds of corruption prosecutions there have been examples of politicians who extorted or embezzled money to enrich themselves and bestow favors to advance their political careers.

In one high-profile case, Finance Minister Darius Valcov resigned in March after prosecutors charged him with taking 2 million euros ($2.14 million) in bribes, including a Renoir painting and gold bars, in exchange for awarding contracts to a local businessman when he was the mayor of a small town.

The mayor of Bucharest, Sorin Oprescu, was suspended after he was arrested last month on charges of being part of a bribery scheme in which where city officials allegedly demanded a percentage from companies in exchange for awarding contracts.

Klemm said Romania's regulatory climate "still lacks cohesion and long-term vision," and called for rules that are transparent, predictable and stable.

The ambassador said Romania had the advantage of a well-educated workforce and resources such natural gas, forests and farmland.

"Romania's potential is great....but so too are the reforms that it must undertake to realize it," Klemm said.

The career diplomat took up his post in September, filling a position that had been left vacant since December 2012.