The Pakistani authorities have deployed thousands of police in the city of Lahore where the Indian Prime Minister, Atal Behari Vajpayee, is expected in a few hours time.

He set out from Amritsar on the inaugural trip of a new bus service between the two countries at 1554 local time (1024GMT). It is the first visit by an Indian prime minister to Pakistan for 10 years.

Speaking moments before the bus set off, Mr Vajpayee said he was very happy that he was going to meet Mr Sharif.

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Mr Vajpayee's 16-strong delegation will be welcomed at the Wagah border crossing by the Pakistani Prime Minister, Nawaz Sharif; they will continue their journey to Lahore by helicopter.

The Pakistani government says it will not allow the visit to be disrupted despite the threat of further protests by Islamic groups.

On Friday about 2,000 people protested in Lahore against the visit.

'Vajpayee go home'

Most of the protesters belonged to Islamic parties, including the influential Jamaat-i-Islami, which has called for a general strike in Lahore to coincide with the arrival of Mr Vajpayee.

Carrying banners proclaiming "Vajpayee go home", protesters vowed to keep the Indian leader from setting foot on Pakistani soil.

In Karachi, a cardboard model bus was burnt during another demonstration against Mr Vajpayee.

Protesters burn an effigy of Mr Vajpayee

Pakistani religious groups fear that a rapprochement between the two prime ministers might lead to the countries' competing territorial claims over Kashmir being forgotten.

Islamic separatists in Indian-administered Kashmir are seeking to break away from Delhi, and they have the support of many in Pakistan.

Separatist guerrillas have stepped up their attacks against Indian forces in Kashmir, apparently in anticipation of Mr Vajpayee's visit.

High on the weekend agenda will be discussions covering the Kashmir conflict and South Asia's nuclear strategy.

Pakistan's Foreign Minister, Sartaj Aziz, has called on India to commit itself to a solution to the Kashmir issue, which he said was the root cause of the tensions between the two countries.

BBC Delhi Correspondent Mike Wooldridge, currently in Lahore, says the reality is that it also remains the issue on which any breakthrough is least likely this weekend.

More realistic is some joint initiative so that they can better manage their nuclear arsenals.

Poetry diplomacy

To coincide with the visit, a book of Mr Vajpayee's poetry has been published in Urdu by a Pakistani pulisher.

It is the first time an anthology of poems by an Indian politician has been published in Pakistan but the publishers say they are not too sure whether it will be a commerical success.

Aftab Hussain of Lahore's Kitab Numa publishing house said the production was a joint effort with the poems translated into Urdu by an Indian, Dr Jameel Akhtar, in Delhi.

He said the gesture had symbolic significance.

'Publicity stunt'

Some South Asian experts believe that the visit is little more than a public relations stunt designed for the international community which has put pressure on both countries to ease tensions following last year's nuclear tests.