A series of dry years - together with population growth - has recently increased the pressure. Both Israel and Jordan rely on the River Jordan – but Israel controls it and has cut supplies during times of scarcity.

The level of the Sea of Galilee has dropped in recent years, sparking fears that Israel's main reservoir will become salinated.

The Palestinians - whose water supply is also controlled by Israel - say supplies are intermittent and expensive, and that the underground aquifer which they share with Israel has become depleted and damaged through overuse. Israelis in the West Bank use four times as much water as their Palestinian neighbours.

On its northern border, Israel threatened military action in 2002 when Lebanon opened a new pumping station taking water from a river feeding the Jordan.

To help ease the crisis, Israel has agreed to buy water from Turkey and is investigating building desalination plants.