Factbox: Who are the separatists targeted by Pakistan's strikes in Iran?

Pakistan said on Thursday it had carried out airstrikes against separatist militants in Iran, the latest step in a tense standoff after Iran's missile and drone strikes in the South Asian nation's border province of Balochistan.

Here are some facts on the group Pakistan targeted and the restive province at the heart of the tension.

WHICH GROUP DID PAKISTAN TARGET IN IRAN?

The Baloch Liberation Front (BLF), which an intelligence official called the target of Pakistan's strikes in Iran, seeks independence for Pakistan's western province of Balochistan.

Ethnic Baloch militants have battled the government for decades for a separate state, saying the central government unfairly exploits the province's rich gas and mineral resources of Balochistan province, which borders Afghanistan and Iran.

The BLF is among the insurgents who often target gas projects, infrastructure and security posts there, but have begun launching attacks in other parts of Pakistan.

They also attack Chinese projects, and occasionally kill Chinese workers despite Pakistan's assurances that it is doing all it can to protect the Chinese projects.

WHAT IS BALOCHISTAN'S SIGNIFICANCE?

The vast province of roughly 15 million people is mostly arid desert and mountainous territory holding untapped mineral wealth.

It is Pakistan's largest province by size, but the smallest by population. It borders Iran's Sistan-Baluchestan province where Pakistan carried out its strikes.

Hundreds of Baloch protesters, many of them women, have protested in the Pakistani capital of Islamabad in recent weeks, making accusations of heavy-handed treatment of those in the province, including enforced disappearances and extrajudicial killings.

Balochistan is a key location in China's huge multi-billion China Pakistan Economic Corridor (CPEC), which is part of President Xi Jinping's Belt and Road initiative.

China has undertaken mining projects and built an international airport and a port in the province's southern coastal town of Gwadar.

Canadian miner Barrick Gold owns a 50% stake in the Reko Diq mine in the province's district of Chagai, with the rest owned by the government of Pakistan and the province. Barrick considers the mine one of the world's largest underdeveloped sites for copper and gold.