Reform of the United Nations Security Council should be based on the principles of equitable regional representation and contribution to U.N. activities, a senior U.N. official visiting Japan argues.

Didier Opertti Badan, 61, president of the 53rd U.N. General Assembly and foreign minister of Uruguay, arrived in Tokyo on Monday for a six-day visit at the invitation of the Foreign Ministry.

The 53rd General Assembly's regular session was held between September and December. As its chairman, Opertti concluded the session by adopting 250 resolutions and some 60 decisions.