China’s iron ore imports in April were nearly flat from a year ago, customs data showed on Tuesday, surprising most analysts, as environmental curbs limiting steel production likely reduced demand for the steelmaking raw material.

Iron ore imports rose slightly to 82.92 million tonnes last month, up 0.8 percent from 82.23 million tonnes a year ago, data from the General Customs of Administration showed.

Iron ore imports slipped 3.3 percent from March, the data showed.

Many analysts had expected an increase in imports on firm demand from steel mills in northern China that reopened on March 15 following government-mandated production restrictions to help meet clean-air regulations.

However, some steelmaking regions have extended or re-imposed the production curbs for failing to meet air quality targets or as smog has returned.

Mills in the city of Xuzhou in Jiangsu, China’s second-largest steelmaking province, were ordered last month to shut for almost a month to meet stricter air quality rules.

Meanwhile, local authorities in the Inner Mongolia autonomous region and Hebei, Shanxi and Shandong provinces will intensify environmental checks after receiving rectification notices from the central government.

“The environmental crackdown will certainly weigh on iron ore demand. Based on the current situation, production curbs will be on a regular basis in more regions,” said Xu Bo, analyst at Haitong Futures.

A large accumulation of iron ore inventories has also reduced the need for imports.

Stockpiles of iron ore at Chinese ports climbed by 1 million tonnes in the week to May 4 to 160.28 million tonne, consultants SteelHome reported. Inventories have declined from a record 161.68 million tonnes in late March.

Source: Reuters (Reporting by Muyu Xu and Tom Daly in BEIJING, and Manolo Serapio Jr in MANILA Editing by Joseph Radford and Christian Schmollinger)