SOFIA (AFP) – Bulgarian President Georgi Parvanov invited US companies yesterday to invest in energy infrastructure in the Balkans to counterbalance strong Russian involvement in the region. «Bulgaria maintains active relations with Russia when it comes to large-scale energy infrastructure projects. But I proposed to President Bush today a clearer, more categorical and firmer commitment by US companies in energy projects here,» Parvanov said. US President George W. Bush, who was in Sofia yesterday on a one-day official visit, also said Bulgaria and the US could cooperate on energy supply diversification issues. Bulgaria’s center-left government has come under considerable criticism by opposition parties for its extensive cooperation with Russia on all major energy projects in the small Balkan state. Russian company Atomstroyexport signed a 4-billion-euro (5.26-billion-dollar) contract in November to build a new nuclear power plant in the northern town of Belene. Parliament then ratified in May an agreement with Greece and Russia to build a 280-kilometer (174-mile) pipeline between the Bulgarian Black Sea port of Burgas and the Greek port of Alexandroupolis, to channel Russian oil from the Caspian Sea to the Aegean. Russia has also announced plans to boost its natural gas transits to Central Europe via Bulgaria. Parvanov said yesterday that he was «friends with George (Bush) as well as with Vladimir (Putin).» «Bulgaria does not have to choose between its friendship with the US and Russia… We can maintain a good relationship with everybody who wants it to be so,» he added. Parvanov has particularly encouraged the US firm Chevron to join the Burgas-Alexandroupolis pipeline project. He has also welcomed the participation of the US-based AMBO consortium in building another trans-Balkan pipeline from Burgas in the east to the Albanian port of Vlore on the Adriatic Sea. «This is an investment in peace and security in the region,» Parvanov said.