US-based companies AES and ContourGlobal, which own two of Bulgaria's largest thermal-power plants, have submitted declarations that they are leaving one of the key employers' organizations in the country.

Both were, until now, members of the Confederation of Employers and Industrialists in Bulgaria, or CEIBG (also increasingly known as KRIB).

This information comes after BIA, BCCI, BICA and CEIBG, the four main organizations, demanded that the government suspend payments above market prices to the AES Maritsa East-1 and ContourGlobal Maritza East-3 power plants for their electricity.

But AES officials are quoted by Dnevnik.bg as saying they submitted their request as early as last week.

The four organization suggest a cap should be imposed on purchase prices for energy produced by the two plants until the EU Commission has had a say on whether payment above market levels is a form of "illegal state aid".

At the end of September, they also asked Chief Prosecutor Sotir Tsatsarov to look into alleged irregularities in the energy sector, including the privatization contract for Maritsa East-1 - a claim AES Bulgaria refuted in a statement, also vowing to provide all the information needed if an inspection is launched.

Under a "roadmap" on reform in the energy sector - a document on which the associations have been working since early in October - the two coal-fired plants should also be nationalized to be later privatized by other companies.

Capital Daily reports it has obtained the letter with AES and ContourGlobal sent to KRIB to announce they were leaving, blaming part of the association's leadership for trying to discredit their activities in Bulgaria.

The two companies on Tuesday co-drafted a declaration with other members of the energy sector to warn the employer associations are going against free-market principles which could undermine reforms in the sector. In their words, measures put forward by employers are threatening "Bulgaria's reputation as a country with secure investment climate."