By Rajasik Mukherjee

Feb 17 (Reuters) - Shares of Australia's BlueScope Steel BSL.AX hit a more than 3-year high on Monday after the steelmaker's half-year underlying profit surpassed market expectations and its upbeat commentary on U.S. tariffs on steel imports.

The stock gained as much as 12.3% to A$25.100, poised to touch its highest level since August 31, 2021. The stock also marked its biggest intraday gain since October 23, 2020.

The broader ASX200 benchmark .AXJO was down 0.6%, as of 0246 GMT.

The country's largest steelmaker reported an underlying net profit after tax of A$176 million ($112.01 million), beating both Visible Alpha consensus of A$171 million and UBS estimate of A$170 million.

"(First half) result was a small beat driven by a strong Australian steel products' $(ASP.AU)$ result," analysts at UBS said in a note.

The ASP division reported an underlying earnings before interest and tax of A$131 million, ahead of Jarden estimates and the second half of fiscal 2024.

CEO Mark Vassella also hinted at potential boost to its profitability due to U.S. President Donald Trump's tariffs on steel imports.

""If prices go up, as we saw last time, then the short answer is, Yes, we stand to benefit," he said, noting that steel prices were up 20% since Trump's tariff announcement a week ago.

North America was BlueScope's biggest revenue-generating geography in fiscal 2024, having accounted for about 43.9% of its total sales.

The Melbourne-based steelmaker also announced an interim dividend of 30 Australian cents per share.

BlueScope also said it expects underlying EBIT in the second half of the year to be in the range of A$360 million to A$430 million, higher than the A$309 million reported in the first half.

The 2022-founded company also projected higher second-half earnings for its North America segment.

($1 = 1.5713 Australian dollars)

(Reporting by Rajasik Mukherjee in Bengaluru; Editing by Rashmi Aich)

((Rajasik.Mukherjee@thomsonreuters.com;))