Analysis By Steven Eke BBC Russian affairs analyst

ConocoPhillips is adding to its existing foreign interests

Keep out of politics, and you're welcome to invest.

That appears to be the message from the Russian government today, after it sold a stake in the country's giant oil company, Lukoil, to an American group, ConocoPhillips.

The sale, worth almost $2bn (�1.1bn), is the biggest in cash terms since the collapse of the Soviet Union.

It is an important signal to potential foreign investors, who have been concerned at the Kremlin's attack on one of the country's top oil companies, Yukos, which many say is politically motivated.

The Lukoil-ConocoPhillips deal appears to have been something of a foregone conclusion, following the intervention earlier this year of Vladimir Putin himself.

The Russian president held an unprecedented meeting in July with the heads of both companies.

Analysts described that as the official blessing for the sale to go ahead.

Foreign investment

They have predicted it may ease the concerns felt by many potential foreign investors, who are keen to tap into Russia's lucrative but still largely unexplored oil and gas reserves.

The Lukoil deal follows a recent, billion-dollar acquisition in the Novatek gas producer by the French company, Total.

Both deals appear to have been dependent on the Kremlin's direct approval. But they also signal that investing in Russia is still viable.

Earlier this week, the Russian government announced it was removing all restrictions on foreign ownership of Gazprom, the world's largest natural gas company.

However, that will only happen after the state has ensured, via mergers, that it has majority control.

Kremlin's 'dual approach'

This appears to highlight the Kremlin's dual approach of trying to entice investment while effectively retaking control of the energy sector.

Underlying this, at least partly, appears to be the desire to prevent political challenges emerging from big business.

And that is what makes Lukoil or Gazprom so different from the Yukos oil giant.

Its chief executive, Mikhail Khodorkovsky, set himself up as a direct challenger to President Putin.

He now languishes in prison, while Russian officials openly discuss which parts of his former empire should go where, and at what cost.