Almaty, October 19 - China's CNPC will sell 33 percent of PetroKazakhstan to Kazakh state oil firm KazMunaiGas, a public relations firm working for Kazakhstan said, to smooth the way for CNPC's $4.2 billion Petrokaz takeover.

State-owned China National Petroleum Corp. (CNPC) said on Monday it agreed to transfer a stake of PetroKazakhstan to KazMunaiGas if the Kazakh government dropped objections to the takeover, and KazMunaiGas confirmed a deal had been reached.

But neither gave any details.

Shareholders in Canadian oil firm PetroKazakhstan, which has all its assets in the Central Asian state, were due to meet in Calgary at 1500 GMT to approve CNPC's $4.18 billion takeover offer.

The PR firm, Paris-based Marston-Nicholson, emailed a statement saying the stake transfer would be 33 percent and that the deal included a joint-venture for CNPC and KazMunaiGas to run the Shymkent oil refinery on a parity basis.

Neither the Kazakh president's press service nor the prime minister's could confirm to Reuters on Tuesday that the latest Marston-Nicholson statement had been approved by the government.

Petrokaz shares leapt 2.4 percent to $54.35 in New York on Monday, slightly below CNPC's offer of $55 apiece, after CNPC and the Kazakh oil company said they had reached agreement on future cooperation over Petrokaz.

CNPC's takeover of PetroKazakhstan has been saddled by problems, including a new law in Kazakhstan that aims to give the government the right to buy foreign-held oil stakes that are put up for sale.

On Friday, Reuters saw a letter from CNPC to the government offering the same terms, but there has been no public confirmation that those details were included in a deal struck on Saturday.

Marston-Nicholson says it is employed by Kazakhstan for public relations and frequently emails English-language statements in the name of the government.

The government has not said whether or not it will seek to use its new powers, signed into law by President Nursultan Nazarbayev on Saturday, in the CNPC takeover.

It has said it objected to the takeover because the Canadian company did not warn it beforehand and because it wanted control over some PetroKazakhstan assets, including the Shymkent refinery, one of only three in Kazakhstan.

Russian oil major LUKOIL has also threatened to take legal action later on Tuesday in an effort to scupper the deal as it believes it has a pre-emptive right to buy out PetroKazakhstan's half of a joint-venture, Turgai Petroleum.

News selected by Luc MATHIAS, source Reuters