The Pakistani Prime Minister, Nawaz Sharif, starts a week-long visit to the United States later today Mondayduring which he will meet President Clinton.

The BBC Islamabad correspondent says their discussions are expected to focus on nuclear non-proliferation, which has dominated relations between Islamabad and Washington since Pakistan's nuclear tests in May.

Pakistan has agreed to sign the Comprehensive Nuclear Test Ban Treaty CTBT next year, but has so far refused to sign the Nuclear Non-Proliferation Treaty NPT, saying nuclear deterrence is now a key element in its security policy.

Mr. Sharif will also meet officials of the International Monetary Fund and the World Bank which have agreed an economic rescue package for Pakistan.