"The results of our checks are excellent," the head of the team from the International Atomic Energy Agency, Marco Gasparini, was quoted as saying in a statement released by the state-run plant.

"We are impressed by the complexity and volume of the work completed under the modernisation plan."

A report and the full conclusions of the IAEA checks will be presented to Bulgaria's nuclear regulator agency, it added.

The 10-day mission, consisting of seven IAEA experts, was invited to assess whether the plant had fully completed the modernisation of its two operating Soviet-built 1,000-megawatt reactors to bring them in line with EU standards.

Kozloduy's modernisation plan, which included 212 measures in total, was accomplished during a series of reactor shutdowns for repairwork between 2002 and 2007.

The plant invited the IAEA mission to check the quality of its fuel after a long-term Kozloduy employee, Georgy Kotev, accused it in his web blog and in media interviews of using dangerous recycled fuel.

Kozloduy's management denied the accusations at the time and did not say Thursday whether the IAEA ever checked the fuel.

European Union safety concerns prompted Bulgaria to shut down four of Kozloduy's total of six reactors in order to join the bloc in 2007.

In order to compensate for the lost capacity and restore its position as a top electricity exporter on the Balkans, the country contracted Russia's company Atomstroyexport and subcontractors Areva and Siemens to build a new 2,000-megawatt facility in Belene, east of Kozloduy.