Singh will undertake a three-day visit to attend the 16th Summit of the NAM, a grouping of 120 countries of the erstwhile Third World, sources said.
Besides attending the NAM Summit, Singh is expected to have bilateral meetings with Iranian President Mahmoud Ahmedinejad and Zardari, they said.
Singh's visit and meeting with Ahmedinejad assumes significance as it will take place at a time when the US is pushing India to reduce engagement with Iran and implement sanctions imposed by some countries over its controversial nuclear programme.
Ahmedinejad had called up Singh in May to invite him for the Summit with an emphasis that expansion of ties in different fields would lead to "considerable achievements" for both nations.
The Prime Minister, on his part, had told him that India attaches great importance to ties with Iran and called for further expansion of cooperation.
The US has been pushing India to cut its oil imports from Iran, which accounts 12 per cent of its total crude imports, as part of implementation of the sanctions imposed on the Persian nation. India has been maintaining that it would implement only those sanctions which are imposed by the UN.
During his stay in Tehran, Singh is expected to have a bilateral meeting with Zardari who would also be there to attend the NAM Summit.
The two leaders are expected to review the progress in bilateral relations in various fields.
