VimpelCom said that one of its three largest shareholders, Altimo, had sent it a letter claiming that the other two, Telenor and Weather II, violated the company’s bylaws, following a deal in February 2012 which saw Telenor increasing its ownership through the acquisition of shares from Weather.

According to a statement from VimpelCom, Altimo has made several assertions, including that Telenor and Weather “formed a ‘group’ holding more than 50 percent voting interest in VimpelCom,” and that the transaction should have triggered a mandatory tender offer. It has called for VimpelCom to “take immediate steps to investigate this matter and consider all available options to ensure that the situation caused by the alleged on-going breach…is resolved.”

Apparently, Altimo has also noted that it is not possible for the supervisory board of VimpelCom to now require Telenor and Weather II to launch a mandatory tender offer, due to “the position taken to date by the Russian Federal Anti-Monopoly Service.” It has urged the supervisory board to “ensure that the alleged control of the company will not be exercised in a manner which fails to protect the rights of minority shareholders,” and to “preserve the status quo at the Supervisory Board level until such time as this matter is fully addressed.”

Reuters reported that Dag Melgaard, a spokesman for Telenor, had branded the assertion that the company is working in concert with Weather as “absurd.” He mooted that the move may be designed to push the VimpelCom share price down, as Altimo is approaching the point in the calendar where it can buy more, following an earlier standstill agreement.

When Telenor announced its deal with Weather, it was said that the deal marked the end of a long-running ownership dispute which started through the combination of VimpelCom with Weather’s Wind Telecom unit. It also saw “certain put and call arrangements” put in place, which could see Telenor increasing its voting rights above 50 percent.