Bulgarian Prime Minister Boyko Borisov on Monday described recent developments related to private gas supplier Overgas as a "plot against the government".

In an interview with private national bTV station, he warned shortage in gas supplies to Overgas and its customers as of January 01 could have "brought about a collapse of the entire energy network of the country and mass protests against the cabinet."

He also made clear neither Gazprom nor Russia itself were to blame for the situation.

Overgas on Thursday signed an agreement with state-owned gas supplier Bulgargaz to receive gas deliveries from the latter to avoid the halt. The day before, reports emerged of a letter from Gazprom Export notifying Overgas it was stopping supplies to the company.

Russia's Foreign Ministry later confirmed there were "commercial issues" between Gazprom and Overgas, but the Bulgarian company denies having any outstanding debts.

Borisov, whose previous government resigned in 2013 after protests over energy prices, called Overgas ?nsolent" over its suggestions state authorities were seeking to "steal" its business.

"They turned to us with a request [for supplies from Bulgargaz], is this called  stealing a business?" Borisov asked rhetorically, adding Overgas customers (more than 55 000 households and 3000 businesses) would have thrown the blame on him and not on the private company if Bulgargaz had not intervened and supplies had been brought to a halt.

"If it is normal for somebody to say at 18:30 on December 31 they cannot cope with their job and then argue their business is being stolen, this is insolent."

Borisov questioned the decision of Overgas to wait until Thursday evening to turn to the government for help.

But Overgas for its part claims it has not prolonged debts to Gazprom or any other company.