Manmohan Singh arrives in the troubled Himalayan region on Wednesday to lead two-day talks with Kashmiris.
It is to be the second such event this year, but Islamist rebels have threatened to disrupt the meeting.
To demonstrate their intent, the Pakistan-based Jaish-e-Mohammed militant group claimed responsibility for four grenade attacks in Srinagar, Kashmir's main city on Monday, which killed one person and wounded 24.
At least 20 people, including 10 police, were wounded when three grenades were lobbed at police patrol parties at separate places in the city.
Another grenade thrown at a tourist bus killed the driver and wounded four tourists at Soura on the city's outskirts, police said.
Islamist rebels have been fighting Indian rule of Kashmir since 1989, with tens of thousands of people killed as a result.
Elsewhere, in what analysts termed a setback to the talks, the main political separatists, the All Parties Hurriyat Conference (APHC), an alliance of two dozen political, religious and community groups, said it would not join the "crowd".
"The Hurriyat considers that the crowd comprising political hypocrites and Ikhwanis (former militants), with no agenda, can hardly produce a result in terms of the permanent settlement of the Kashmir problem," the Hurriyat chairman, Mirwaiz Umar Farooq, told a news conference.
An official in the prime minister's office in New Delhi said Singh would go ahead with the conference despite the Hurriyat boycott and the violence. "The prime minister will chair the meeting for one-and-a-half days. It's going to be very substantial," the official said.
Kashmiri political parties who have fought local elections and some separatist leaders are likely to attend the meeting which aims to widen the dialogue in the region.
The Hurriyat has held two rounds of direct talks with Singh, the latest this month.
The Hurriyat has also talked to Pakistan, which controls part of Kashmir but like India, claims it in full.
India has also been engaged in a peace dialogue with Pakistan for the past two years which has made little progress on the core issue of Kashmir.