France, March 12 -- A third of fertiliser shipped by sea comes from the region and cannot make it to the global market as Iran has effectively closed the Strait of Hormuz.

That has sent global fertiliser prices soaring, with the UN expressing concern in particular about the impact on developing countries. Gulf a key manufacturer

Natural gas is a key feedstock to make artificial fertilsers, and with its ample gas supplies the Gulf region has become a key manufacturer.

The region produces nearly half of the sulphur sold worldwide and a third of urea - "the most widely traded fertiliser of all", said Sarah Marlow, global editor for fertilisers at Argus Media.

It also produces a quarter of globally traded ammonia, another feedstock f...