SEOUL (Reuters) - South Korea's Samsung Electronics 005930.KS and SK Hynix 000660.KS have asked a local supplier to the boost supply of a key chipmaking chemical to guard against any production disruptions, an official at the supplier said on Tuesday.

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The move by the two chipmakers to secure supplies of hydrogen fluoride comes after Japan said earlier this month that it would tighten curbs on exports of high-tech materials used in smartphone displays and chips to South Korea, threatening to disrupt the global supply of microchips consumed by the likes of Apple Inc AAPL.O and Huawei Technologies Co.

"They are checking almost every day to secure more supplies from us," said the official at Foosung Co 093370.KS which provides hydrogen fluoride to the two chip giants, adding that the chipmakers offered to run the quality tests for its product.

The official declined to be named due to the sensitivity of the matter.

Samsung and SK Hynix declined to comment whether such requests were made.

South Korean chipmakers rely on Japan for most of the materials affected by the export curbs, although they source some hydrogen fluoride from China and South Korea.

Stockpiling is not regarded as a viable option for hydrogen fluoride as it is highly toxic.

Foosung is currently a supplier to Samsung and SK Hynix.

South Korean media Yonhap Infomax reported earlier on Tuesday that the two firms have requested local suppliers to boost their shipment of hydrogen fluoride to reduce their reliance on Japanese imports.

A SK Hynix official said the company was running a test of some South Korean hydrogen fluoride materials, but did not provide further details.

The company said its President Don Kim flew to Japan on Tuesday to discuss the export controls with its Japanese suppliers.