Asia's largest refiner posted first-quarter net profit of 14.76 billion yuan ($2.3 billion) under Chinese accounting standards, with refinery throughput up 2.7 percent year on year to 61.78 million tonnes, or about 5.01 million barrels per day (bpd).

Sinopec's refining margins could be squeezed in the second quarter, with the company seeking to replace lost Iranian barrels as Washington looks set to end all sanction exemptions on Iranian imports from May.

The Chinese refiner processes more Iranian oil than any other company.

The state oil and gas group reported realised crude oil prices of $57.66 a barrel, down 3.6 percent from a year earlier.

Its realised natural gas prices were $7.07 per thousand cubic feet, up 12.6 percent year on year.

Sinopec's first-quarter crude oil production slipped 0.8 percent from a year earlier to 70.81 million barrels while natural gas output rose by 6.7 percent to 255.8 billion cubic feet.

(Reporting by Chen Aizhu; Editing by David Goodman)