David Loyn reports from Islamabad

His comments came amid reports that Pakistan was preparing to test a new medium-range missile capable of carrying nuclear warheads.

Mr Kharrazi, on a visit to Pakistan, said many countries in the Middle East had been worried that Israel was the only nuclear power in the region, so they welcomed Pakistan's action.

At the same time, the Iranian minister called for restraint on all sides, and repeated that Iran's own nuclear research programme was entirely peaceful.

Kamal Kharrazi on Pakistan's tests

Mr Kharrazi's trip was planned before Pakistan's announcement last week that it had exploded six nuclear test devices in response to India's five nuclear tests earlier in May.

The tests by the two countries were denounced by the international community.

Israeli concern

Iran said it detected no radiation in its border area near Pakistan's Chagai test site

Israel itself voiced concern after the Pakistani tests that Baghdad and Tehran would be encouraged to acquire their own nuclear weapons.

Israeli Deputy Defence Minister, Silvan Shalom, said Tel Aviv did not see Pakistan's tests as a threat to Israel, and did not view Pakistan as an enemy.

But Shalom told Israel Defence Forces' radio that the fact that Pakistan was a Muslim country was "definitely a factor to be taken into consideration".

Many military analysts believe Israel has a nuclear weapons capability, but the Jewish state has neither confirmed nor denied reports that it has some 200-300 nuclear warheads.

Pakistan preparing new missile

Dr Samar Mobarik Mand, head of Pakistan's nuclear test programme

Meanwhile, Pakistan has said it is ready to test a new medium-range missile, which it could arm with nuclear warheads.

According to BBC correspondent David Loyn, Pakistan's latest nuclear blast was a test warhead for the new missile, which could hit the Indian capital in less than seven minutes.