* April daily output soars to highest since May 2014
* Mills ramp up production after winter curbs lifted in mid-March
* Coke output was highest since Sept 2017 (Adds detail)
BEIJING, May 15 (Reuters) - China's daily crude steel output in April rose to its highest in at least 4 years, official data showed on Tuesday, as mills boosted production to take advantage of high margins after the end of winter output curbs.
Overall steel output in the world's top producer climbed to 76.7 million tonnes in April, up 3.7 percent from March and up 4.8 percent from April a year ago, according to data from the National Bureau of Statistics (NBS).
Daily average output reached 2.56 million tonnes last month, the strongest since at least May 2014.
The rise came after cities in northern China lifted stringent capacity restrictions imposed during the five-month winter heating season as part of Beijing's efforts to clear up its notorious foul air.
The official heating season ended on March 15, although major steelmaking hub Handan extended a 50-percent output capacity curb until the end of March.
Output over the first four months of the year was 288.97 million tonnes, up 5 percent on the same period last year, NBS data showed.
Production of coke, used in steelmaking, fell 3.6 percent in April to 36.72 million tonnes compared to the same period last year due to an environmental crackdown across the country. But output in April was the highest since September 2017.
(Reporting by Muyu Xu and Josephine Mason Editing by Joseph Radford)