The conference, the world's sole multinational negotiating forum for disarmament, spent much of 2009 stuck on procedural wrangles raised by Pakistan after breaking a 12-year deadlock to agree a programme of work.
The impasse on Tuesday suggested 2010 would be another year of halting progress.
Pakistan, which tested a nuclear weapon in 1998, is wary of the proposed focus in the programme on limiting the production of fissile material, which would put it at a disadvantage against longer-standing nuclear powers such as India.
It therefore has an interest in delaying the start of substantive talks, diplomats say.
Even in the darkest days the agenda was adopted, because everything can be discussed under the agenda, said one veteran official, unable to recall a similar delay in the past.
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Adoption of the agenda at the start of the annual session is normally a formality, but Pakistan Ambassador Zamir Akram took the floor to call for the agenda to be broadened to cover two other issues.
Akram said the 65-member forum should consider conventional arms control at the regional and sub-regional level, in line with a United Nations General Assembly resolution sponsored by Pakistan and passed last year.
The conference should also negotiate a global regime on all aspects of missiles, he said.
It is not our intention to create an obstacle but it's also not our intention to create a situation which is oblivious to what is happening around us, Akram said.
The move forced the conference president, Bangladesh ambassador Abdul Hannan, to adjourn the meeting for consultations to find a consensus. He said he hoped to resume on January 21 with a renewed discussion of the agenda.
Sergei Ordzhonikidze, the former Russian diplomat who heads the U.N. in Geneva and is secretary of the conference, said failure to adopt the agenda would be a move backwards, arguing that it was flexible enough to include all topics of concern. But Akram said Pakistan did not want to work with a programme that was frozen in time.
Reaching a consensus is likely to prove difficult, as India rejected a discussion of regional conventional arms control, arguing that the conference should focus on global issues.
Diplomats said Pakistan's attempt to include regional arms control appeared directed at its bigger and better-armed neighbor.
The U.N. General Assembly also called on the conference last December to agree a 2010 work programme including immediate negotiations to ban the production of fissile material, in a resolution sponsored by Canada.
(Editing by Stephanie Nebehay and Noah Barkin)