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Prime Minister Manmohan Singh was to pay a landmark visit to troubled Indian Kashmir on Tuesday, a day after heavily-armed militants killed eight soldiers in the deadliest attack in the region for five years.

Singh was to be accompanied by Sonia Gandhi, the president of the ruling Congress party, for a two-day visit in which he will inspect major infrastructure projects and inaugurate part of a railway line to connect north and south Kashmir.

It is the first time the premier has visited the Indian-controlled part of the divided Himalayan territory -- which has been the scene of two wars with Pakistan -- since June 2010 and comes less than a year before India goes to the polls.

More than a dozen armed rebel groups have been fighting Indian forces since 1989 for the region's independence or its merger with Pakistan and tens of thousands of people, mostly civilians have died in the fighting.

Armed violence had been declining steadily since the early 2000s but the region has been tense following the execution in February of a local man over a deadly 2001 attack on the national parliament in New Delhi.

Mohammed Afzal Guru's execution, carried out in a New Delhi prison without first informing his family, triggered widespread protests in Kashmir where many doubted his guilt.

Much of Kashmir has since been put under curfew repeatedly while protests and strikes have disrupted daily life.

Police and paramilitary forces have been deployed in strength across the region ahead of Singh's visit, with additional check points along major highways.

But despite the high security, a group of militants managed to stage an attack Monday on a troop convoy on the outskirts of the region's main city Srinagar.

Eight soldiers were killed and 13 others were wounded, a police official said on condition of anonymity.

The militants, travelling by motorbike, opened fire on the army vehicles which were en route to a nearby base, before lobbing a grenade at one of them, police sources said.

Hizbul Mujahideen, a local pro-Pakistan militant, group claimed responsibility.

It was the deadliest attack on Indian security forces since July 2008 when a landmine killed nine soldiers on a bus on the outskirts of Srinagar.

Chief Minister Omar Abdullah was among those who condemned Monday's attack, saying it was "aimed at restoring the shattered morale of the militants".

Abdullah is an ally of Singh but has criticised the Delhi government for showing what he regards as a lack of political will to resolve the underlying tensions in what is India's only Muslim-majority state.

"The Kashmir issue needs to be addressed politically. Economic packages are not a solution to the issue nor can it be found on the point of a gun," Abdullah said recently.

In an editorial on the eve of the visit, the local Kashmir Reader daily said the security measures put in place during the visit "only proves to be a reminder of broken promises".

The three main separatist groups have called for a strike Tuesday to protest against Singh's visit.

"This is a protest against the forcible military occupation of Kashmir and we want to give the Indian prime minister this message that by hanging Afzal Guru, New Delhi has sent the entire Kashmiri people to the cross," Syed Ali Geelani, a top separatist leader, said in a statement.

Officials say a few dozen youths have been detained in police stations to "prevent protests" during the visit, although separatist leaders put the figure at hundreds.

Singh is expected to review a federally funded reconstruction package he had announced nine years back after taking office for his first term.

He will also inaugurate part of an ambitious project expected to link the landlocked Kashmir valley with the massive Indian railway network by 2018.

During a visit in 2009, Singh inaugurated another section of the rail link and also reiterated his commitment to an economic reconstruction package worth around $4 billion.

Officials in the local government say only about only 40 percent of the allocated resources have been used so far.