Workers at Bulgaria's moribund Kremikovtzi steel mill Tuesday protested to reiterate their demand for unpaid salaries, reported dpa. Hundreds of workers blocked the front gate of the mill near the capital Sofia, complaining that they have not been paid since July. The protest had been on hold after the mill management had promised "all measures" and find money for August and July salaries. The unions are unhappy with the Kremikovtzi majority stakeholder, the Indian-born steel magnate Pramod Mittal, brother of Lakshmi, the chief executive of the world's largest steel concern, ArcelorMittal. ArcelorMittal expressed interest in buying the remaining 25 per cent of the Kremikovtzi capital from the Bulgarian government, but the deal never materialized. Another potential investor, the Ukrainian tycoon Konstantin Zhevago's Vorskla Steel, also seemed interested and has backed Kremikovtzi by supplying raw material since August, when the mill went into a deep liquidity crisis. Vorskla director for Bulgaria, Victor Demyanyuk, however announced Monday it was terminating the deal with Kremikowtzi, saying its workers "became accustomed to holding strikes instead of working." The current output of Kremikovtzi, a Communist-era giant, is at 70,000 tons, less than half of its 150,000-ton capacity. One of the key hurdles to efficient investment into the mill is the cost of upgrades needed to be in line with EU environmental standards. Bulgaria joined the European Union in 2007.