Any possible military dimensions of Iran's nuclear program can be clarified if the details of a preliminary deal sealed in April between Tehran and six world powers are implemented, the head of the U.N. nuclear watchdog said on Monday.

Iran has been stalling an investigation by the International Atomic Energy Agency into its nuclear program. The agency is yet to set a deadline for a final assessment, although it has said the process will not be open-ended.

The investigation is running in parallel with political talks between Iran and the six powers which are meant to end in a final agreement at the end of this month.

"I am confident that the clarification of issues with possible military dimensions is possible within a reasonable timeframe if Iran implements the measures envisaged in the (preliminary)... announcement," IAEA head Yukiya Amano said, according to the text of a speech.

It is the first time Amano has clearly linked the technically separate U.N. investigation into possible military dimensions of Iran's past activities to the political talks Iran is holding with the United States, France, Britain, China, Russia and Germany.

As part of the initial deal reached in April in Switzerland, Iran was to implement a so-called Additional Protocol giving the IAEA more intrusive access to facilities in Iran. Iranian officials have been giving conflicting messages about what kind of access would be granted to crucial military sites.

"Implementation by Iran of the Additional Protocol will ... significantly increase the Agency�s ability to provide credible assurance about the absence of undeclared nuclear material and activities in (Iran)," Amano said.

Diplomats have voiced concern that once sanctions relief is granted to Iran in exchange for it curbing its nuclear program under any final deal, there will be little incentive for Tehran to disclose all details of its past activities to the IAEA.

By Reuters