By Jonathan Saul

LONDON (Reuters) - Maersk Line, the world's biggest container shipping company, has stopped port calls to Iran as Western sanctions pressure on the Islamic Republic mounts, a spokeswoman said on Tuesday.

Many of Iran's imports, including food and consumer goods, are transported by sea via container and bulker ships.

While food and consumer items are not targeted by sanctions, a growing number of Western firms, especially shipping related companies, are pulling back from trade with Iran due to the complexities of deals, whilst also fearing losing business elsewhere.

"Maersk Line has ceased to call in Iran," a spokeswoman for the unit of Danish group A.P. Moller-Maersk said.

"This is a pragmatic decision based on an assessment of balancing the benefits of doing limited business in Iran against the risk of damaging business opportunities elsewhere particularly the U.S."

In recent days Iran's rial currency has lost about a third of its value against the dollar, emerging as a fault line in Iran's economy as the country resists foreign pressure over its nuclear programme, denying Western accusations that it is aimed at making weapons.

For Iran's clerical rulers, who face threats of war from abroad and subdued discontent at home, preventing any destabilizing economic crisis is a pressing concern.

"To date, Maersk Line's business in Iran has involved transporting foodstuffs and other goods, for example vehicles, for the benefit of the general civilian population. It is with regret that it is ceasing these activities," the spokeswoman said.

"Maersk Line will maintain a dormant business entity in Iran and will look to resume business should the sanctions regime be eased."

In 2011 the U.S. blacklisted major Iranian port operator Tidewater Middle East Co, which operates seven terminals in Iran including the biggest container port Bandar Abbas. That led Maersk Line to suspended operations at several ports.

Since 2011, it has called at the small northern Iranian container port of Bushehr. The spokeswoman said Maersk Line halted loading cargo bound for Bushehr on September 30 and stopped loading outbound cargo from Bushehr on September 24.

"Maersk Line ceased its acceptance to all other ports than Bushehr in 2011," the spokeswoman said. "The discontinuation of services to and from Bushehr unfortunately reflects the difficulties servicing Iran as a whole."

(Editing by Keiron Henderson)