"We think that the claim is pretty much baseless," Sistema's Mikhail Shamolin told CNBC, speaking from the St. Petersburg International Economic Forum, referring to the multi-billion dollar lawsuit that Rosneft filed on May 2.
Shares of the Russian conglomerate Sistema have dropped by over 40 percent since the legal claim was submitted, with Rosneft upping the amount under dispute from an initial 106.6 billion rubles ($1.9 billion) to 170.6 billion ($3 billion) last week.
Rosneft is claiming that Sistema removed assets from Bashneft when the latter was owned by Sistema and prior to Rosneft taking a controlling stake in the smaller Russian oil company last October. A Moscow court rejected the case on May 10 which prompted a short-lived recovery in Sistema's stock price.
Shamolin denied the lawsuit is actually a front for Rosneft chairman and close ally of Russian President Vladimir Putin, Igor Sechin and Sistema Chairman Vladimir Yevtushenkov to settle old scores emanating from the days of the mass and rapid privatization of Russian industries which began in earnest in the early 1990s.
"We are not personalizing this, it is not Mr. Sechin, it is Rosneft as a company that is filing the lawsuit," asserted Shamolin.
The Sistema president then pointed to some elements of the claim, including Rosneft's dispute of the cancellation of Treasury shares which he argues is an "absolutely typical transaction" that companies all over the world frequently undertake, as examples of the egregiousness of Rosneft's position.
Rosneft, the integrated oil company which is majority owned by Putin's government, has also included the effect of ruble depreciation in the lawsuit.
"How can Sistema as a company be responsible for what happens to the ruble?" asked Shamolin.
"We have a claim and we are dealing with this in court in a civilized way and we believe that our legal position is pretty tight and we'll see how it goes," he concluded.
In response, a Rosneft representative with knowledge of the company's information policy, said that "arbitrage is a professional argument of the specialists in the area of the corporative law."
"It doesn't imply public discussion. We will defend our position in court, not in media," the representative said.