Novatek $6 bln supply deal threatens Gazprom contract

* Gazprom says Inter RAO should honour contracts

* Inter RAO Novatek proposals more "attractive"

By Vladimir Soldatkin and Nastya Lyrchikova

MOSCOW, Nov 5 (Reuters) - Novatek (NVTK.MM), Russia's No.2 natural gas producer, has asked its shareholders to approve a 177.3 billion rouble ($6 billion) domestic gas supply deal with power trader Inter RAO.

If the deal is signed, Gazprom, one of Novatek's main shareholders, would see its gas purchases from Inter RAO reduced to nothing, said two sources at Inter RAO.

According to a ballot mailed to Novatek shareholders and seen by Reuters, the company's board has recommended its shareholders approve a deal to supply Russia's power trader Inter RAO IRAO.MM and its regional generation company OGK-1 (OGK1.MM) with around 65 billion cubic metres (bcm) of gas from 2010 to 2015.

Gazprom has current contracts to supply Inter RAO, which owns power stations across the former Soviet Union, and OGK-1 with natural gas from 2007 to 2012.

The Inter RAO sources told Reuters that the company and its OGK-1 unit would not terminate the contracts with Gazprom if they sign with Novatek, but would reduce their gas purchases to zero.