Fitch Ratings said it has upgraded PetroChina Co Ltd's long-term foreign currency issuer default rating (IDR) and senior unsecured ratings to 'A+' from 'A'.

The ratings agency said it has also upgraded PetroChina's long-term local currency IDR and senior unsecured ratings to 'AA' from 'A+', upgraded its short-term local currency IDR to 'F1+' from 'F1' and also affirmed its short-term foreign currency IDR at 'F1'.

Fitch said the rating action is triggered by its upgrade of China's country ceiling to 'A+', foreign currency long-term IDR to 'A+' and local currency long-term IDR to 'AA-'.

PetroChina's ratings reflect its leadership position in China's oil and gas markets, substantial oil and gas reserve levels, sound exploration and production capabilities and the integrated nature of its energy businesses from upstream to downstream, Fitch said.

The ratings factor-in PetroChina's government support, high barriers of entry to the oil and gas industry and the strong energy demand growth in China arising from significant economic progress. The ratings also incorporate the company's robust financial profile, characterised by its strong profitability, healthy cash generation, low leverage and high liquidity, Fitch added.

Fitch said PetroChina's recent A share debut in Chinese mainland will further strengthen its financial position.