TOKYO — New Zealand’s Prime Minister John Key on Tuesday urged Japan to join talks for a planned Pacific free trade deal that advocates hope will prove a boon to the region’s economy. Key, in a joint press address with Japanese Prime Minister Yoshihiko Noda, said the talks over the Trans-Pacific Partnership (TPP) were gaining momentum with Mexico and Canada expected to get on board soon. “My strong hope is that Japan will join the negotiations,” he told reporters. “I think the prime minister and I share a common view that we should be pushing deeper integration of the Asia Pacific economies,” Key said. The nine countries currently involved in the talks are Australia, Brunei, Chile, Malaysia, New Zealand, Peru, Singapore, the United States and Vietnam. Noda, who faces a party leadership election this month, has said Japan would benefit from free trade deals, but faces intense domestic opposition, particularly from farmers, a powerful voter bloc. “Regarding TPP, I explained that my views have not changed since I announced the decision in November to enter into consultations toward participating in the TPP negotiations with countries concerned with an eye toward joining the full negotiations,” Noda said. “We concurred that we would continue our close communication with each other,” he said. The TPP began life as a small grouping but gained significance when the United States joined in 2008, with President Barack Obama seeing it as a tool to advance American economic interests in the Asia-Pacific region. Advocates say it would prove a useful way of counteracting the growing clout of China in regional trade, and insist the inclusion of Japan’s vast economy would give the pact a huge shot in the arm. Key said Noda and his ministers have expressed “a high level of ambition” about joining the free trade talks. “We both want to see a rules-based architecture that gives greater certainty to investors and those who want to trade within the region,” Key said. “With Canada and Mexico about to join the negotiations, TPP has a real momentum,” Key said.