SRINAGAR: Anxious to quell anti-India protests in held Kashmir, Indian forces are carrying out their most severe crackdown in more than two decades against civilian protesters, arresting more than 8,000 this summer across the disputed Himalayan territory, police said Monday.

That includes 450 or so civilians being held, possibly for up to six months without trial, under a harsh security law criticised as a human-rights violation.

India has said the suspected separatist rebels ─ and civilians who help them ─ are undermining the country's territorial integrity and forcing authorities to keep India-held Kashmir (IHK) under tight control.

"This is, so far, the biggest crackdown against miscreants," said a senior police officer, requesting anonymity because he was not authorised to share details of the crackdown.

Police say they have detained at least 8,000 people on suspicion of participating in anti-India protests and throwing rocks at government troops, including more than 400 people picked up in nighttime raids in the last week alone. Many detained have been subsequently released on bail as well, police said.

Officers are still hunting for at least 1,500 more people suspected of participating in protests, according to three other top police officers overseeing the crackdown operations.

The officers also spoke on customary condition of anonymity.

For weeks, Indian authorities have carried out nighttime raids, rolling curfews and stops at roadblocks, but have failed to stop the rebel attacks and angry public rallies.

On Monday, government forces were battling a group of suspected rebels near a highway running by saffron-rich Pampore town, on the outskirts of the region's main city of Srinagar.

Read more: Suspected rebels attack government compound in held Kashmir

Gunshots and grenade blasts were heard from the site, where units of the army's special forces, paramilitary soldiers and counterinsurgency police had cordoned off and encircled a building, according to an officer who spoke on condition of anonymity, in keeping with department policy.

The officer said the two sides were exchanging intermittent gunfire. One soldier was reported injured.

Scores of people gathered on nearby streets to chant anti-India slogans in a show of solidarity with the rebels.

Rebel groups have been fighting in the region since 1989, and more than 68,000 people have been killed in the armed uprising and ensuing Indian military crackdown.

While anti-India protests are somewhat common during warmer summer months, this year's have been especially fraught amid widespread anger over the killing of a popular rebel commander by Indian forces in July.

India has responded with a clampdown that has nearly paralysed daily life.

More than 80 civilians have been killed and thousands injured in clashes with police and paramilitary troops.

Two policemen have also been killed and hundreds of government forces injured in the clashes.

Rights activists expressed alarm over the government's targeting of protesters. Almost all of the thousands of suspects arrested in a crackdown in the early 1990s were either suspected militants or people accused of harbouring them.

"The state is arresting noncombatant activists and protesters at such alarming and unprecedented rate," local human rights lawyer Pervez Imroz said. "This crackdown marks the Indian government's failure to reach to a political solution of the issue."

Activists have long campaigned against India's armed forces special powers act, which gives troops sweeping powers to interrogate or shoot suspects on sight.

Also, under the act, federal army and paramilitary soldiers cannot be prosecuted in civilian courts unless federal approval is granted.