Official sources said they expect Singh to place before Talbott India's proposals on the twin issues.

Singh's visit comes in the backdrop of Prime Minister Atal Behari Vajpayee's statement in Parliament that India remained committed to a dialogue with key interlocutors ``with a view to arriving at a decision regarding adherence to CTBT.

``These are critical meetings'', US State Department spokesman James Foley said at a news briefing.

He added Washington hoped India and Pakistan would be prepared to make forward steps in the direction of the international community's agenda for defusing the situation caused by the nuclear explosions in South Asia.

Talbott is slated to meet Pakistani Foreign Secretary Shamshad Ahmad in London onTuesday.

Washington, which clamped sanctions on India, has been trying to persuade Delhi and Islamabad to immediately sign the CTBT. But, both have so far refused to do so.

The outcome of the visit will depend on whether US President Bill Clinton would visit India and Pakistan later this year.

Singh and Talbott have met thrice in the last three months in Washington, Frankfurt and New York.

A senior US official was quoted as saying that Washington was certainly hoping for something from these meetings ``probably the last before we have to take a decision on the President's visit slated to take place in November''.

Soon after the nuclear tests in May, Washington had stated that Clinton's visit to India was under review.

Significantly, American officials have termed as ``encouraging'' recent statements from India.

With the economies of East Asia, including Japan, and now Russia in trouble, the US business community is anxious to resume normal business with India.