NEW DELHI, FEB. 25 -- Prime Minister Rajiv Gandhi announced today that India has successfully tested a missile developed by its own scientists and capable of carrying large warheads at least 150 miles.

"After a number of necessary test launches, we plan to induct Prithvi {Hindi for 'Earth'} into our defense forces," Gandhi told a cheering Parliament this afternoon.

The prime minister said that only the United States, the Soviet Union, France and China had developed missiles of similar range and capability.

While the new missile appears to be some distance from deployment, its development apparently gives India a significant new advantage in its military relationship with Pakistan. With a range of 150 miles, the missile could be targeted on much of Pakistan, including the major cities of Lahore and Karachi.

The new weapon places India at a stage in tactical battlefield missile technology similar to that reached by the superpowers in the 1960s. But in southern Asia, "it's better than anything their neighbors have got," said one military expert.

The weapon's development also raises the question of whether India now could deliver a miniaturized nuclear warhead by missile, should New Delhi decide to develop one.

India exploded a "peaceful nuclear device" in 1974, but denies it has developed nuclear weapons.

Given the missile's relatively short range, military specialists said today that its use as a nuclear delivery vehicle could prove dangerous. "You never know which way that stuff is going to blow," said one, referring to fallout from a nuclear explosion.

While India has purchased a wide array of modern weapons "off the shelf" from the Soviet Union and the West, it also has pursued its own weapons-development program for years using the country's huge reservoir of highly educated scientists and engineers.

In addition to missiles, it is engaged in a new project to develop its own warplane.