Iron ore shipments to China, the world's top steel producer, have slowed in the past few weeks as ports are overwhelmed by large stocks of the raw material accumulated ahead of a giant leap in prices from next month.

While China's booming steel sector would ensure strong demand for iron ore, imports of which jumped 40 percent last year, buyers were concerned about higher prices and new tax restrictions on steel exports, industry officials said Wednesday.

Top miners CVRD and Rio Tinto bagged a 71.5 percent increase in iron ore contract prices for sales to Asia's major steel mills this year, as China prepares to suck in more than one-third of the world's seaborne ore.

"In April, the new prices will take effect. There is a lot of iron ore now at all major ports," said an industry official in Hong Kong.

From April 1, China would cut or abolish export tax rebates for some low-end steel products, shipments of which have boomed since mid-2004, the traders and industry officials said.

The move is aimed at curbing iron ore and power usage in the world's top steel market, which churned out 273 million tons of steel last year, up 23 percent.

A Beijing-based iron ore trader with an international firm said some small traders and steel mills had faced difficulties getting import licenses since the government tightened controls from the beginning of March.

Source: Shenzhen Daily/Agencies