The price of APT, an intermediate tungsten product of which the mainland contributes about 80 percent of world supply, has more than doubled this year as China's depleted and power-starved mines fail to replace dwindling stocks in Europe and the United States.

The mainland is also offering less APT for export as it processes more of the material to make cemented carbides and machine tools for domestic use.

Prices will keep rising for the next few weeks, suppliers said Wednesday, but they noted mines are resuming output and that buyers will not be able to pay prices much higher than current levels.

``The market will be very firm in the coming months, but it won't be as crazy as in March,'' said one supplier.

APT prices rose more than 30 percent last month.

Suppliers said they are offering APT at US$215 to US$220 (HK$1,677 to HK$1,716) a tonne unit. Last week it was quoted at US$180 to US$200 a tonne unit, a measure equal to a hundredth of a tonne. At the beginning of the year it traded at about US$90.

China's crackdown on illegal mining has cut supply, while electricity shortages have closed mines supplying tungsten ore from the start of the year.

Officials said power supply had improved with spring rains in the south, where most of China's tungsten is mined.

``Some mines are running as normal, but compared to the strong demand, concentrate is still in short supply,'' a trader said.

Some traders said speculators had contributed to the shortage by building up ore stocks.

``Maybe they will sell out at a very high price,'' said one.

But a shortage clearly exists.

One trader said Zigong Cemented Carbide, a major Sichuan supplier, had stopped two lines producing APT and tungsten oxide due to a shortage of raw materials.

Zhuzhou Cemented Carbide in Hunan is hunting for raw materials because supply from its mines is limited.

Zhuzhou, China's top producer of cemented carbides used in saws and drills, produces APT at a new 10,000-tonne plant in Chenzhou and consumes most of its output in-house.

A tonne of tungsten ore costs in the region of 100,000 yuan (HK$94,270), compared with 60,000 yuan early last month, one supplier said.