The CEO of Sibur, the largest petrochemicals company in Russia and Eastern Europe, on Tuesday said the second quarter of 2019 may be "a good moment" to go ahead with an initial public offering.

The company is in the midst of building its largest-ever expansion project, western Siberia petrochemical complex ZapSibNefteKhim, said Sibur Chief Executive Officer Dmitry Konov. The facility is expected to be completed in the second quarter of next year, which then opens the door for further discussions on listing the company's shares, he noted.

"It may be a good moment to discuss," Konov told CNBC's Geoff Cutmore at the Eastern Economic Forum in Vladivostok, Russia.

"The first stage is Moscow, and then we'll see what we do internationally," the CEO said, referring to the stock exchanges where the company would first list.

But Konov said there is "not a set timetable" and the decision to go ahead would depend on how favorable market conditions are and whether the shareholders find the deal attractive enough to sell their stake.

Sibur's largest shareholder is billionaire Russian gas tycoon Leonid Mikhelson, who owns 48.5 percent of the company, according to a Reuters report. Mikhelson's business partner Gennady Timchenko owns 17 percent, while China's Sinopec and Silk Road Fund control 10 percent each, the news outlet said.

"We're talking to the banks, we're talking to get the feeling whether it would be a right moment to move on or it cannot be," he said.

"And our shareholders, I believe, are pretty happy with the performance of the company. So, for them it's really a decision of whether they see an attractive market, then they would go (ahead). Attractive market is not only the valuation of Russian equities, but also the global petrochemical cycle. These two factors our shareholder do take into account," he told CNBC.

On the size of the IPO, Konov said it's "a little bit too early" to discuss such details, but he suggested Sibur could list about 15 percent of its shares.

Several media outlets earlier reported that Sibur's listing could happen by the end of 2018. Those reports, citing unnamed sources, said the company was looking to float 10 percent to 15 percent of its shares to raise $2 billion to $3 billion.