WASHINGTON, Dec 7: US Defence Secretary Donald Rumsfeld begins a visit to India and Pakistan this week for talks on the sale of sophisticated missiles and other weapons to South Asia's two nuclear neighbours.

He is scheduled to arrive in New Delhi on Dec 9 and may visit Islamabad either on Wednesday or Friday although the Pentagon is refusing to disclose the itinerary of his visit to Pakistan. Since he is attending President Hamid Karzai's inauguration in Kabul on Tuesday, Mr Rumsfeld may visit Islamabad first before flying over to New Delhi.

The Bush administration appears determined to go ahead with the proposed arms sales to India and Pakistan despite criticism that it could further fuel a regional arms race and political instability at a time when delicate peace talks are being held between the two countries.

Although India has criticized the $1.2 billion arms package for Pakistan, it is equally keen to buy weapons from Washington. India has indicated that it plans to discuss with Mr Rumsfeld a possible purchase of the Patriot missile system. The Patriot is a ground-based missile system that can defend against ballistic missiles, cruise missiles and aircraft.

The visit comes as Pakistan is negotiating to buy F-16 fighters and other advanced military equipment from the US. The two nuclear-armed South Asian nations, which have fought three wars in the past five decades and are still struggling to resolve the Kashmir dispute, are already developing new offensive medium- and long-range missile systems.

India's ambassador to the United States Ranendra Sen recently told journalists that he had discussed the prospect of buying Patriot missiles with Prime Minister Manmohan Singh during a visit to New Delhi last month.

The sale could have political consequences across the border in Pakistan. It would give ammunition to the parties opposed to President Pervez Musharraf's alliance with the United States.

Some opposition groups are already arguing that the United States is pro-India, and are urging Gen Musharraf to abandon slow-moving peace negotiations with New Delhi.

Gen Musharraf wants to resolve the 57-year-old Kashmir dispute through talks, but India has focused on improving trade ties, cross-border travel and other diplomatic confidence-building measures.

Diplomatic observers in Washington say that President Musharraf, who has recently expressed his own impatience with the peace talks, would have more difficulty defending them if a major US-India arms deal was perceived in his country as shifting the military balance further in India's favour.

Pakistan's likely response would be to ask for more sophisticated weapons, including F-16 fighter jets, to counter India's defences, analysts said. Pakistan reportedly wants to buy between 19 and 25 aircraft, which cost around $25 million each, in the first half of next year.