Visiting Mexican President Enrique Pena Nieto reacted guardedly Wednesday to Japan's attempt to retain tariffs on rice and some other farm products under the Trans-Pacific Partnership free-trade agreement.

"For items each country wants to withhold (from tariff elimination) and differences between countries, separate negotiating tables have been set up, and they should therefore be dealt with there," he told a news conference in Tokyo.

Before the Mexican leader backed Japan's bid to join the TPP talks during a summit with Prime Minister Shinzo Abe this week, he said in written replies to questions from Kyodo News that Tokyo should respect the TPP principle of eliminating all tariffs.

During the news conference that concluded his four-day visit, Pena Nieto declined comment on specifics of the negotiations. But he said he has supported Japan's bid to join the TPP talks, given the gains made so far from the free-trade agreement between Japan and Mexico.

The bilateral accord, which took effect in 2005, has produced "extremely good results," he said.

Mexico is one of the seven countries to have voiced support for Japan's TPP membership. Four other members — the United States, Australia, Canada and New Zealand — have yet to finalize their positions.

Japan declared last month its desire to enter the TPP talks. But Tokyo's goal of protecting domestic farmers from cheap imports has left some members cautious about its possible entry.