Pakistan's Foreign Ministry says it has swapped a list of nuclear facilities with India, as part of an agreement prohibiting attacks on such installations.
The countries have routinely exchanged these lists on the first day of the year since 1992, under an agreement signed two decades ago.
Thursday's exchange was carried out as normal, despite tensions from November's deadly attacks in Mumbai by suspected Pakistani militants.
On Wednesday, Pakistani President Asif Ali Zardari told U.S. President George Bush by phone that any Pakistani involved in the attacks would be dealt with sternly.
But India's home minister, P. Chidambaram, said Pakistan "is in a state of denial" about the possible involvement of its citizens in the violence.
Earlier Wednesday, U.S. media reported that a leader of the Pakistan-based militant group Lashkar-e-Taiba admitted he helped plan the Mumbai attacks.
Pakistani authorities arrested militant leader Zarah Shah in December under intense international pressure to crack down on his group.
India says the gunmen who attacked Mumbai were Pakistanis trained and equipped by Lashkar-e-Taiba, which has had close ties to Pakistani intelligence services in the past.
Pakistan says India has failed to provide evidence of the attackers' nationalities.
Some information for this report was provided by AFP, AP and Reuters.