TEHRAN - Caspian Sea states declared in Tehran on Tuesday they would not let their soil be used for an attack on any of them, an apparent response to speculation the United States could resort to force in its nuclear row with Iran.

The Islamic Republic is embroiled in a standoff with Western nations which accuse Tehran of seeking atomic weapons, a charge Tehran denies. Washington has refused to rule out military action if diplomacy fails to resolve the row.

The declaration followed a speech by Russian President Vladimir Putin calling on the Caspian nations not to let any third country use their territory for an attack, a comment apparently directed at former Soviet state Azerbaijan.

The U.S. military has inspected airfields in Azerbaijan, which has a partnership deal with NATO, amid Russian media speculation they could be planning to use the facilities in a possible strike on Iran. Azeri officials deny any such plan.

Iran, Russia, Kazakhstan, Azerbaijan and Turkmenistan said "under no circumstances will they allow (the use of their) territories by third countries to launch aggression or other military action against any of the member states."

Also in the final declaration, they acknowledged the rights of all signatories to the Non-Proliferation Treaty -- which includes Iran -- to develop peaceful nuclear energy.

Iranian President Mahmoud Ahmadinejad, who insists Tehran will not stop atomic work he insists is peaceful, praised the Caspian declaration as "very strong".

The presence of Putin, the first Kremlin leader to visit Iran since 1943, has been watched because of Russia's potential leverage, on behalf of fellow world powers, to rein in Iran using its trade and nuclear supply ties with Tehran.

"We should not even think of making use of force in this region," Putin told the summit.

He turned up in Tehran after shrugging off a Russian report about a plot to kill him during the trip. Russian officials had suggested he might change his plans. Iran dismissed the report.


'WARDING OFF HOSTILE FORCES'

Ahmadinejad welcomed Putin and the other leaders in his opening address with a call for closer cooperation on security issues and deeper economic ties.

"This cooperation -- which is intended to prevent military competition in the sea and also warding off hostile forces and at the same time fighting organised crime -- will require the establishment of a regional body in the near future," he said.

Putin is due to hold talks with Ahmadinejad, discussions Russian officials said would focus on Iran's nuclear programme. Moscow says it sees no evidence of a military programme and is resisting Western calls for new sanctions.

"We signed today a declaration which confirms the right of every nation to develop peaceful nuclear programmes without restrictions, that is also something we are going to discuss," Putin said before the bilateral talks.

Russia has been alarmed by mounting talk in the West that the row could result in conflict. France has been among the most vocal of the world powers warning of a possible war.

As well as meeting Ahmadinejad, Putin was expected to see Supreme Leader Ayatollah Ali Khamenei, who under Iran's clerical rule has the final say in all state matters.

The U.N. Security Council has imposed two rounds of limited sanctions on Iran, which were backed by Russia and five other world powers -- the United States, France, Germany, Britain and China. Washington and Paris are pushing against Russian and Chinese resistance for a round of harsher, broader sanctions.

Putin is likely to discuss a dispute over Russian delays in building the Bushehr atomic power plant, Iran's first. Russia says Iran is behind in payments but Iran says they are up to date and that Moscow is bowing to Western pressure.

The summit aimed to bring the five states closer to a deal on how to divide the Caspian Sea and its huge oil and gas reserves but no final agreement was reached although the leaders outlined economic and other areas for more cooperation.