"Twelve people from the Malikhel clan have been admitted to the main district headquarters hospital," Khan said.

The fighting broke out when people of the Malikhel clan tried to divert water to their fields, and men from another clan tried to stop them, Khan said. Many of the ethnic Pashtun people who inhabit both sides of the Pakistani-Afghan border are well armed.

Pakistan has faced a shortage of water this year after light rain and snow over the past winter.

As populations and demand grows, analysts say disputes over water are likely to become more common, not only within communities but between countries.