(Adds segment revenue, CEO comment)
Feb 20 (Reuters) - The world's biggest miner BHP Billiton reported a 25 percent rise in underlying half-year profit on Tuesday, helped by robust metals prices, and said its focus remains on cutting debt and boosting shareholder returns.
BHP said its plan to sell its onshore U.S. shale assets, which it has in its books at $14 billion, was progressing to plan with initial bids expected in the June quarter.
It also brushed off calls by activist investor Elliott Advisors to change its structure, with listings in both Britain and Australia, saying that the costs and risks of collapsing the dual listed structure outweigh potential benefits.
Underlying profit for the half year ended Dec. 31 rose to $4.05 billion from $3.24 billion a year ago, below a forecast of $4.30 billion, according to Thomson Reuters I/B/E/S.
"Higher commodity prices and a solid operating performance delivered free cash flow of US$4.9 billion. We used this cash to further reduce net debt and increase returns to shareholders through higher dividends," Chief Executive Andrew Mackenzie said in a statement.
The miner declared an interim dividend of $0.55 per share, up nearly 38 percent from last year.
It cut net debt by 23 percent to $15.4 billion during the period, and said it was on track to reach its $10 billion to $15 billion target before year-end.
Including a previously flagged $1.8 billion exceptional charge arising from a change in U.S. corporate taxes, net profit fell to $2.02 billion.
Revenue rose 16 percent during the half year to $21.78 billion, with copper revenues jumping nearly 52 percent, backed by stronger prices and higher production from the Escondida mine in Chile.
Revenue from iron ore mining, BHP's biggest division, rose 4.2 percent, while oil was up 8.5 percent.
BHP maintained guidance for production of 275 million to 280 million tonnes of iron ore in the fiscal year to June 30. (Reporting by Rushil Dutta in Bengaluru; editing by Richard Pullin)