Japanese Prime Minister Shinzo Abe discussed strengthening cooperation with gas-rich Qatar as he met emir Sheikh Tamim al-Thani in Doha on Wednesday as part of a regional tour.
The two leaders agreed to strengthen cooperation in the political and security fields, they said in a joint statement.
Abe's tour of the Gulf is seen as his latest push to promote nuclear technology exports.
And the Japanese government says Qatar and Kuwait have shown an interest in nuclear safety, out of concerns that neighbouring countries plan to build nuclear plants.
In May, Japan signed a nuclear cooperation deal with another Gulf state, the United Arab Emirates, during a similar visit by Abe.
A day later, he visited Turkey and signed a long-awaited deal to build a sprawling nuclear power plant on the country's Black Sea coast, in a milestone for the Japanese nuclear industry.
