TOKYO (AFP) - Japan 's main opposition party on Thursday pressed Indian Prime Minister Manmohan Singh to work to eliminate nuclear weapons as New Delhi seeks cooperation on civilian atomic energy. Singh was wrapping up a three-day visit to Tokyo where he signed a major loan agreement and pledged to expand military links in a sign of growing cooperation between the two Asian nations. However, Japan has been hesitant about cooperating with India on nuclear energy. As the only nation to have suffered nuclear attack Japan only reluctantly backed India's landmark nuclear technology deal with the United States earlier this month. "We hope that India maintains transparency of its nuclear sector and contributes to efforts towards an elimination of nuclear weapons," Yukio Hatoyama, secretary general of the main opposition Democratic Party, told Singh. India refuses to sign the nuclear Non-Proliferation Treaty, arguing it is unfairly excluded. Singh replied that India hoped to develop nuclear power to cut the greenhouse gas emissions blamed for global warming, according to an opposition official who attended the talks. Japan also champions nuclear power. Singh, speaking Wednesday at a joint news conference with Japanese Prime Minister Taro Aso, said it was India's "sincere desire to strengthen and develop our cooperation with Japan in civilian nuclear energy." "But I do recognise the sensitivity of this issue in Japan and therefore ... we will move at a pace at which the Japanese government and people are comfortable with," Singh said. Aso has advocated building relations with the fellow democracy to offset frequent tensions with China. Both Aso and Singh were heading later Thursday to Beijing for an Asia-Europe summit. Hatoyama met Singh after a cancellation by Japan 's chief opposition leader Ichiro Ozawa, who for the second time this month said he was too ill for public events. Ozawa's health has increasingly become a concern for the opposition, as it makes gains in its goal of ousting Aso's conservative Liberal Democratic Party, which has been in power for all but 10 months since 1955.