Employees of the Lead and Zinc Complex (LZC; OTZK), the largest Bulgarian producer of non-ferrous metals in the southern city of Kardzhali, will renew protests on Tuesday due to the uncertain future of the plant.

OTZK has been out of operation in the past five months due to the plant's failure to meet environmental safety requirements.

OTZK owner Valentin Zahariev also failed to complete the investment program of the plant and to pay salaries to a total of 519 employees for six months.

Employees of the Lead and Zinc Complex were on strike for about a month due to unpaid wages and social security contributions.

The workers started receiving their money back in mid-April, as Zahariev raised cash through the sale of the Gorubso mines in the southern town of Madan.

Gorubso-Madan was likewise in dire straits, with workers protesting due to unpaid salaries.

After the state interfered, the mines were sold to a company owned by Nikolay Valkanov and became operational again.

Businessman Nikolay Valkanov took over the concession of the Gorubso Madan mines from Zahariev.

Valkanov is a former VP of Multigroup, the company of Bulgarian tycoon Iliya Pavlov, who was shot dead in 2003.

Valkanov currently owns "Minstroy" and Gorubso Zlatograd, another mining company in Southern Bulgaria, and holds the concession for the "Varba" mine.

As OTZK workers started receiving payments, Prime Minister Borisov announced that there would be a change of ownership of the plant.

Borisov vowed that the talks for the potential sale of the plant with the creditor banks would take no more than a month.

OTZK workers, however, decided not to wait until the end of one-month and said that they would block traffic at a key junction in Kardzhali for one hour.

The trade unions at the plant attributed the renewal of protests to the lack of any information about the talks for change of ownership of OTZK.