A bomb has exploded, injuring three people and two other explosives defused on the route of the first India-Pakistan bus across Kashmir ahead of its inauguration this week.

A police source said three civilians were injured in the explosion at Hanjivira village, about 35km north of Srinagar, capital of the Indian-controlled portion of Kashmir, on Tuesday.

The explosive was placed along the highway that will be taken Thursday by the inaugural service of a passenger bus between Srinagar and Muzaffarabad, capital of Pakistani-controlled Kashmir. 

The blast occurred soon after a bomb squad defused two powerful bombs placed in plastic bags along the same highway in nearby Palhalan. The bombs weighed 70kg and 60kg respectively, the officer said.

"Troops detected two roadside landmines buried under soil at Palhalan, which were defused later," a police spokesman said.

"The mines were very powerful. The troops have averted a major tragedy."

Reuniting families

The bus has been hailed as a way of reuniting families divided after the partition of the state in 1947 by a de facto ceasefire border known as the Line of Control.

But groups fighting a 15-year war of attrition in Indian-held Kashmir that has left thousands dead, earlier this week labelled the bus a "coffin", and urged Kashmiris to shun the service.

The road is used daily by hundreds of civilian and military vehicles, and police maintain round-the-clock surveillance.

PHOTO CAPTION

Indian troops have defused two powerful landmines on the highway to be used by a landmark bus service set to be launched this week to link divided Kashmir. (AFP)