The two groups had contacted Spanish oil firm Repsol separately to say they were interested in buying its 4.7-billion-euro ($6.4 billion) stake in Gas Natural, the paper said, citing people close to the process.
Spanish company Repsol has a 30-percent stake in Gas Natural and wants to sell most of the investment so as to leave itself with a five percent share in the gas firm.
Repsol has been selling assets to replace income lost after the nationalisation of its Argentinian subsidiary YPF by Cristina Kirchner’s government in April 2012.
Spanish lender CaixaBank, which is the largest single investor in Repsol with a 12-percent stake and in Gas Natural with a 34-percent stake, approves of Temasek and Sinopec as potential investors, the paper said.
Spanish business daily Expansion said Repsol also was considering an alternative approach of taking over the whole of Gas Natural after selling some of its assets, but this scheme was opposed by CaixaBank.
In February, Repsol announced it was selling a part of its liquefied natural gas business to Dutch-anglo group Royal Dutch Shell for $6.65 billion.
The group’s 2012-2016 strategic plan proposes 19 billion euros in international investments, of which 80 percent is destined for exploration and production.
The strategy includes investing two billion euros in Brazil, 2.3 billion euros in the United States, 1.2 billion euros in Venezuela, 400 million euros in Russia and 20 million euros in Spain.