NEW DELHI, India — When an Indian interceptor rocket rammed a ballistic missile Nov. 27 some 50 kilometers above Ballasore in the eastern part of the country, it demonstrated a capability similar to Israel’s Arrow-2. In June, India will attempt to match the U.S. PAC-3 with a lower-altitude test of the Prithvi Air Defence (PAD) system.

Both tests mark a big step toward putting India in an elite group of nations with defenses against such missiles, said Vijay Kumar Saraswat, who is considered the father of Indian missile-defense efforts and who leads missile programs at the Defence Research and Development Organisation (DRDO), the state’s research lab.

The PAD has two intercept modes, each of which is designed to hit a target within four minutes: exo-atmospheric, or above 50 kilometers; and endo-atmospheric, or lower than about 30 kilometers, Saraswat said.

For exo-atmospheric intercepts, the system’s main sensor is the Israeli Green Pine radar, which has a 600-kilometer range. India imported two Green Pines three years ago, one in operating condition and one as a kit that was subsequently assembled.

The lower intercepts are guided by a radar acquired from another country, DRDO sources said. They declined to identify the specific country.

The interceptor rocket has a liquid-fueled first stage that uses two propellants and oxidizers, and a solid-fuel second stage with a gas thruster that can turn the rocket at more than five Gs. The missile carries sensors to guide it to its target.

The program has two phases. In the first one, expected to be complete by 2009, there will be three tests each of the endo- and exo-atmospheric interceptors, Saraswat said.

The second phase will include more tests, and will include homegrown interceptors with ranges beyond 100 kilometers. It will end by 2012, when the system goes into operational service, Indian Air Force sources said.

When deployed, the PAD will include multiple radars and their control centers, interceptor batteries and their control centers, spread out over as much as 500 kilometers, Saraswat said.

The system includes one radar system that tracks both the incoming missile and the outgoing interceptor, another that helps classify the incoming weapon and sends data to the interceptor batteries, command-and-control computers, and a transmitter to help guide the interceptors, another DRDO scientist said.

Work on the PAD began in 2000 with a planned $1 billion development budget. The system is being designed and developed at the missile complex in Hyderabad in southern India by engineers at three DRDO laboratories: the Defence Research and Development Laboratory, the Imarat research center and Advanced Systems Laboratory.

All the parts of the system, except the main radar and the interceptor guidance packages, were developed in India, DRDO sources said.

One Indian defense ministry official said India was determined to build such defenses, even if they cost billions of dollars and come under criticism.