WASHINGTON, Dec 9: The United States and India are believed to have developed some differences over New Delhi's expected purchase of a missile defence system from Washington, diplomatic sources told Dawn.

According to these sources, India wants to purchase the latest PAC-3 version of Patriot missiles while the United States is offering an earlier, PAC-1 version, used in the two Gulf wars.

The two countries have been involved in a substantive dialogue for supplying the Patriot missiles defence system and Deep-Sea Rescue Vehicles to India. US Defence Secretary Donald Rumsfeld, who arrived in New Delhi on Thursday, was expected to finalize the deal during his two-day stay in the Indian capital.

But diplomatic sources in Washington believe that India's demand for the latest PAC-3 version of the missile defence system could delay the deal. Policy-makers in New Delhi believe that if the Patriot deal goes through, they will not have to worry about the proposed $1.2 billion US arms package for Pakistan.

The Patriots will drastically improve India's military capability, giving it a huge strategic advantage over both China and Pakistan. Patriot is a long-range, all-altitude, all-weather air defence system to counter tactical ballistic missiles, cruise missiles and advanced aircraft.