QUETTA, Pakistan (AFP) - A bomb attached to a bicycle injured at least 13 people near a Shiite Muslim mosque in Pakistan's south-western city of Quetta on Wednesday, police said.

The bicycle was parked in front of a private hospital, close to the mosque in the Satellite Town area of Quetta, the capital of the oil and gas-rich province of Baluchistan, which borders Afghanistan and Iran.

But senior police official Fayaz Sumbal said the target of the attack was not yet clear as the injured were mainly bystanders.

There was also no immediate claim of responsibility. The Taleban have stepped up violence ahead of Pakistan's general elections on May 11.

Baluchistan is also troubled by a separatist insurgency demanding political autonomy and a greater share of profits from the region's natural resources.

Sectarian bloodshed has also been on the rise. Late Tuesday, a suicide car bomber killed six people and wounded more than 30 others in Hazara Town, a Shiite dominated area in Quetta.

On Feb 16, a giant tractor bomb killed 90 Shiites from the ethnic Hazara minority in Quetta. On Jan 10, 92 others were slaughtered by suicide bombers at a snooker hall elsewhere in the city.