"I want to make clear we regret the Indian government's decision to proceed with this test," State Department spokesman Richard Boucher said.

"Missile testing has the potential to increase tensions in the region and we hope that India will consider the impact of missile tests under the current circumstances," Boucher told reporters.

Earlier Friday, India announced it had successfully test-fired a Prithvi ("Earth") missile, one version of which analysts say is nuclear-capable with a range of 150 kilometres (93 miles), off its eastern coast of Orissa.

A 250-kilometre (150-mile) version of the missile is at an advanced stage of development, they said.

In addition to regretting the test, Boucher said speculation about perceived imbalances in weaponry between India and arch-rival Pakistan could further destabilize South Asia, especially given the fact that the two countries conducted tit-for-tat nuclear tests in May 1998.

"We're troubled by some of the conclusions that are being drawn," Boucher said, stressing that the United States believed there was "rough parity" in the weapons capabilities of India and Pakistan.

"We're worried that the perceptions of strategically significant differences which we don't think exist could lead to actions which would help further destabilization," he said. US oversight agency questions rationale behind missile defense: report