* Xi says week of talks made "step-by-step" progress
* Headway made, says Lighthizer, hopeful despite much work to do
* Both China and U.S. yet to offer details on outcomes
* Sources say little sign of agreement on major sticking points (Recasts with Xi comments)
BEIJING, Feb 15 (Reuters) - Talks between China and the United States this week made important progress, President Xi Jinping told top U.S. trade negotiators on Friday, adding that efforts would continue in Washington next week to resolve their bruising trade war.
Xi met U.S. Trade Representative Robert Lighthizer and U.S. Treasury Secretary Steven Mnuchin after a full week of trade negotiations at senior and deputy levels in Beijing, and called for a deal both sides could accept, state media said.
U.S. duties on $200 billion worth of imports from China are set to rise to 25 percent from 10 percent if no deal is reached by March 1 to address U.S. demands that China curb forced technology transfers and better enforce intellectual property rights.
After the conclusion of talks, which included a banquet on Thursday, Mnuchin said on Twitter that he and Lighthizer had held "productive meetings" with Xi's top economic adviser, Vice Premier Liu He.
"The consultations between the two sides' teams achieved important step-by-step progress," Xi said, according to state television.
"Next week, both sides will meet again in Washington. I hope you will continue efforts to advance reaching a mutually beneficial, win-win agreement," Xi said during a meeting at Beijing's Great Hall of the People.
He added that China was willing to take a "cooperative approach" to settling bilateral trade frictions.
Lighthizer told Xi the senior officials had "two very good days" of talks.
"We feel that we have made headway on very, very important, and very difficult issues. We have additional work to do but we are hopeful," Lighthizer said, according to a foreign media pool video.
Neither country has yet offered new details on how the world's two largest economies might de-escalate the tariff war that has roiled financial markets and disrupted manufacturing supply chains.
Although U.S. President Donald Trump said this week that an extension of the tariff deadline was possible if a "real deal" was close, Larry Kudlow, director of the National Economic Council, has said the White House had made no such decision.
But several sources informed about the meetings told Reuters there was little indication negotiators had made major progress on sticking points to pave the way for a potential meeting between Xi and Trump in coming weeks to hammer out a deal.
"Stalemate on the important stuff," said one of the sources, all of whom requested anonymity because the talks are confidential.
"There's still a lot of distance between parties on structural and enforcement issues," said a second source. "I wouldn't quite call it hitting a wall, but it's not a field of dreams either."
A third source told Reuters the White House was "irate" over earlier reports that the Trump administration was considering a 60-day extension of the tariff deadline.
Lighthizer and Mnuchin left their Beijing hotel on Friday afternoon without taking questions from reporters.
'SLEIGHT OF HAND'
Reuters reported earlier that in recent meetings China has pledged to make its industrial subsidy programs compliant with World Trade Organization rules and end those that distort markets, but had offered no details of how it will do so.
The offer has been met with scepticism from U.S. negotiators, in part because China has long refused to disclose its subsidies.
And some in U.S. industry have been unimpressed with the extent of other reported Chinese offers to address U.S. concerns, such as Beijing's proposal to hike purchases of U.S. semiconductors to $200 billion over six years.
John Neuffer, president and chief executive of the Semiconductor Industry Association (SIA), told Reuters the offer would be "akin to an accounting sleight of hand" and "an attempt to rearrange our supply chains and drive them deeper into China".
Neuffer added, "We are confident U.S. government negotiators will wisely dismiss this offer and continue pushing for meaningful reforms that create a fair and level playing field for U.S. companies doing business in China."
The proposal, first reported by the Wall Street Journal, was part of a "recycled" package of goods purchase offers that Beijing first presented in the spring of 2018, a source told Reuters.
Many U.S. lawmakers and business groups have urged Trump in recent weeks not to settle for a deal based largely on increased Chinese purchases of farm and energy commodities.
Trump has said he did not expect to meet Xi before March 1, but White House spokeswoman Sarah Sanders has raised the possibility of a meeting between the leaders at the president's Mar-a-Lago retreat in Florida.
China has long denied Washington's accusations of trade abuses, and it has retaliated to U.S. tariffs with its own duties on American goods.
Some trade experts say China appears focused on securing a Xi-Trump meeting, in the hope that it would make a near-term deal to limit or reduce tariffs more likely. (Reporting by Michael Martina; Additional reporting by Lusha Zhang, Min Zhang, and Philip Wen; Editing by Kim Coghill and Clarence Fernandez)