BRUSSELS (AP) ― Japan and the European Union agreed at a summit meeting Saturday to begin negotiations on a free trade agreement that would deepen economic ties between two of the world’s largest economies. As a bloc, the EU is the world’s largest economy; Japan is number four.

Negotiations will be preceded by what the leaders called a “scoping exercise” to ensure that both sides share the same goals and level of ambition for the negotiations.

At the summit, held in the picturesque Castle of Val-Duchesse, the leaders also agreed to work toward greater nuclear safety worldwide and to create closer political ties. The meeting was attended by Japanese Prime Minister Naoto Kan; Herman Van Rompuy, president of the European Council; and Jose Manuel Barroso, president of the European Commission.

“Radiation does not stop at national borders, and neither should our collective responsibility,” Barroso said at a joint press conference after the meeting. “So when we talk nuclear, we talk global.”

Japanese officials are sensitive about being stigmatized by the nuclear accident that followed the devastating earthquake and tsunami of March 11. They believe that some tests on imports of Japanese food are too stringent, even when the food is produced far from the site of the disaster. And they say the loss of tourism, even in areas far from any contamination, will hurt the country’s economy.

Barroso sought to allay those concerns Saturday.

“We firmly believe that Japan is safe and open for business,” he said.

But the negotiations on a free trade agreement may be difficult.

The European Union imposes a 10 percent tariff on goods imported from Japan while Japan imposes no tariff on those imported from the European Union.

Japanese officials told the Associated Press before the meeting they see the issue as relatively simple.

But EU officials see it as more complex, and they insisted successfully that the talks also take into account non-tariff barriers to trade and investment. They say, for example, that in the EU public procurement is open and they want to make sure that is the case in Japan, as well.

EU officials also say that, while foreign investment is equal to 30 percent of gross domestic product in the EU, in Japan the figure is only 3 percent, and the reasons for that must be explored in the talks to come.

Still, all three leaders said the benefits of successful negotiations would be very significant. Kan said the outcome “would be important for the global markets.”

Van Rompuy agreed.

“The potential economic and political results are huge, in terms of jobs, growth and a shared destiny,” he said.

The leaders said that, in the political sphere, Japan and the European Union share the same values, including support for democracy and human rights, and should work together in resolving problems from the Middle East and North Africa to North Korea. They also said they would cooperate in showing leadership on the issue of climate change.

Van Rompuy is fond of writing haiku, a form of Japanese poetry, and he ended his post-summit statement with one that referred to the earthquake, the tsunami and the nuclear disaster.