(CNN) - US and Chinese negotiators meeting this week in Beijing have agreed to extend trade talks until Wednesday, according to a spokesperson for the office of the US Trade Representative.
It's a fresh sign that discussions are moving in a positive direction as staff for the two sides meet face to face for the first time since President Donald Trump and his Chinese counterpart Xi Jinping agreed in December to restart talks.
China's Commerce Ministry said ahead of the meeting that it would last only two days.
The Trump administration, in its own notice announcing the US delegation, did not specify how long the visit would last, saying only that talks between the two countries were "beginning Monday."
A person familiar with the matter told CNN that negotiators between the world's two largest economies needed more time to discuss issues that were part of the agenda.
On Tuesday, China also announced it would approve the imports of five new varieties of genetically modified crops, a move that would allow more American farmers to sell more biotech seeds to China.
The decision included long-awaited approvals by US farmers, including corn and soybeans produced by DowDupont and BASF.
"The approval of the seeds is a big deal," said Craig Allen, president of the US-China Business Council. "It allows the seed companies, farmers and traders greater transparency. Hopefully, this also implies that in the future, there will be a more predictable process."
This week's talks, the first at the staff level, appear to have made continued progress on additional Chinese purchases and greater market access as a confidence builder, while leaving tougher issues aside.
"It seems there have been no fist fights internally between the two delegations," said another person familiar with the progress of the talks, who described them as "constructive."
US officials were always planning to return to Washington on Wednesday night.
"No flight changes have been changed. No hotel stays have been extended," said this person.
For now, it remains unclear exactly how deeply negotiators have been able to delve into tougher issues including forced technology transfers and subsidies.
"I suspect these will be matters of continuing discussion going forward as negotiations move up another level to the principals," said this person.
US officials are expected to host China's top trade negotiator, Vice Premier Liu He, in Washington later this month, another source told CNN on Monday.
The trade talks are playing out amid the ongoing US government shutdown and in the shadow of a March 2 deadline announced by Trump in December.
The President agreed after his meeting with Xi at the G20 summit in Argentina to suspend plans to escalate tariffs from 10% to 25% but only for 90 days while talks proceed.
Trump triggered market anxiety by suggesting in December that he was still prepared to go ahead with the increased tariffs if a trade deal can't be reached, calling himself "Tariff Man," but has been bullish on progress of talks since then.
He tweeted on Tuesday morning, "Talks with China are going very well!"
In recent weeks, both presidents have sent encouraging signals of wanting to broker a deal, but what remains unclear is exactly what parameters have been set, if any, in reaching an agreement and whether it will include permanent changes by China on what the US sees as necessary structural reforms.
The US delegation to Beijing is being led by Jeff Gerrish, deputy to the US Trade Representative Robert Lighthizer.
In addition to Gerrish, the official delegation will also include David Malpass, the Treasury Department's undersecretary for international affairs.
Also traveling were USTR's chief agricultural negotiator Gregg Doud; the Department of Agriculture's undersecretary for trade and foreign agricultural affairs Ted McKinney; Commerce Department undersecretary for international trade Gilbert Kaplan and the Energy Department's assistant secretary for fossil energy Steven Winberg.
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