The move comes after U.S. President Donald Trump launched a trade probe on Thursday against China and other exporters of cheap steel into the U.S. market, raising the possibility of new tariffs.

The United States has already slapped a series of anti-dumping duties on steel imports from South Korea and other countries. The United States is the biggest market after China for South Korean steel products, and accounted for about 12 percent of the country's total exports of the metal in 2016, according to South Korea's steel association.

A South Korean steel company official told Reuters that the government and South Korea's steel industry should consider all measures including filing a complaint with the WTO in response to "deepening U.S. trade protectionism."

A senior official at South Korea's trade ministry said the government was considering its response to the U.S. move.

"We are open to all possible options including filing a complaint with WTO but nothing has been decided. We will decide after listening to opinions of the Korean steel industry," the official said.

The ministry official and the company official asked not to be identified because of the sensitivity of the matter.

"The government will closely monitor related trends and will actively respond together with private companies," the Ministry of Trade, Industry and Energy said in the statement. It said the issue would be raised at WTO committee meetings set to be held on April 25-27 in Geneva.

Trade minister Joo Hyung-hwan will have a meeting with Korean steel companies on April 27 to gather opinions and discuss ways to deal with the situation, the ministry said.

POSCO (>> POSCO) shares closed up 2.5 percent on Friday and Hyundai Steel (>> Hyundai Steel Co) ended up 1.1 percent, outperforming the wider market's <.KS11> 0.7 percent rise.

"Rising trade protectionism is negative to the steel industry overall, but the industry has been recovering, helping cushion the negative impact," said Will Byun, an analyst at NH Investment & Securities.

POSCO said on Tuesday that its first-quarter operating profit more than doubled, beating its estimate on solid demand from China.

(Reporting by Hyunjoo Jin and Jane Chung; Editing by Tom Hogue and Susan Fenton)

By Hyunjoo Jin and Jane Chung

Stocks treated in this article : Hyundai Steel Co, POSCO