US Experts are surprised by the Pakistani claims about the size and number of the devices and are suggesting that Islamabad is either fibbing about the number of tests or has fudged production of fissile material in the past.

An analysis of the seismic data recovered in India thus far confirms that Pakistan conducted one test, with a second experiment a "possibility", said the scientists. They, however, could not verify the existence of the other three tests.

This analysis was based on the wave forms created by Pakistan's test at Chagai Hills, in Baluchistan, yesterday. The seismic wave forms show one test distinctly, with another trough suggesting a second one as conceivable.

But as far as the other three tests are concerned, "wecannot confirm them. The wave forms on their own do not show up as nuclear tests", said a nuclear scientist.

Meanwhile, experts in the United States have also said that Pakistan's five-for-five nuclear tests are not all they are bruited to be, downgrading both the number and strength of the devices Islamabad claims to have exploded. According to preliminary estimates, Pakistan had exploded as few as two nuclear devices, both in the range of 5 to 10 kilotons, US intelligence sources were quoted as telling American media. This also tallies with estimates made by various Indian establishments. The scientific data released here in New Delhi after the tests held at Pokhran on May 11 and 13 showed the thermonuclear device to be 43 kilotons, the fission device to be of 12 kilotons, and the three low-yield devices to be 0.5, 0.3 and 0.2 kilotons.

Meanwhile, the US Geological Survey in Golden, Colorado, said that Pakistani's strongest test had a preliminary magnitude of 4.9 on the Richter scale. India's strongestblast registered 5.4 and, according to some US experts, had a tonnage of between 25,000 and 30,000.

The Incorporated Research Institutions for Seismology, a scientific group in Washington, said instruments at its station in Pakistan recorded the blast as having a magnitude of 4.8, equal to between 8,000 to 15,000 tons of high explosive. That would make its size about half to a third of the Indian device.

On the other hand, unnamed US officials were quoted as saying Prime Minister Nawaz Sharif's announcements that Pakistan had conducted "five successful nuclear explosions," levelling the score with India, was probably political propaganda intended for domestic consumption. The first statement by A.Q. Khan, the chief of Pakistan's nuclear programme, claimed two tests, while the subsequent assertion by the Foreign Minister Gohar Ayub Khan spoke of three devices being tested.

The officials also discounted the possibility of Pakistan having armed its medium range Ghauri missile and the bogey of an imminentIndian attack, saying both were aimed at the domestic audience. One expert, however, claimed that the, "data from the Pakistani blast suggested it was the right size for a warhead on a medium-range missile."