The United States says there has been progress but no final deal in talks with Japan, crucial to advancing the ambitious 12-country Trans-Pacific Partnership trade deal.
Negotiations have failed to achieve a breakthrough just days before US President Barack Obama arrives in Tokyo on a state visit. Obama has made the TPP a key goal of his administration.
Intense negotiations this week narrowed the gap between the two sides but considerable differences remain, US Trade Representative Michael Froman said after his meetings with Japanese Minister for Economic and Fiscal Policy Akira Amari.
"The round we just completed was focused but difficult. After more than 20 hours of negotiations we continue to make progress and we are now faced with a reasonable number of outstanding issues."
The two sides have been wrestling in particular over Japan's barriers to importing US cars and farm products.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The specific outstanding issues were not mentioned by Froman. But he said negotiators "have worked to be as creative as possible to address Japan's political sensitivities."
Even so, the overall goal is "meaningful access" to the Japanese market, a goal that all TPP partners share, Froman said in a statement.
Amari stressed big differences remain, according to Kyodo News.
Kyodo said senior US and Japanese negotiators will meet again in Tokyo on Monday.
The TPP, a key plank of Obama's foreign policy, would establish a free trade pact among 12 countries responsible for about 40 per cent of global GDP.
Obama's goal is anchor the US firmly to the region and put market-opening pressure on China, which has been excluded from the talks.
But huge sticking points remain. The US and Japan, the world's first and third largest economies, are fighting to protect important domestic industries.
Washington and other parties to the talks, which include Canada, Chile, Mexico and several Asian countries, say Japan's unwillingness to open its lucrative agricultural market is a deal breaker.
Earlier this month, Japanese Prime Minister Shinzo Abe instructed Amari to accelerate the negotiations ahead of Obama's arrival in Japan on April 24 for a state visit that had at one point been expected to crown the TPP.
