ZURICH, Aug 13 (Reuters) - Switzerland’s lifting of some economic sanctions against Iran on Thursday should allow Swiss-based companies to take advantage if the U.S. and European Union eliminate their own trade curbs.

The Swiss government, acting after a July 14 deal between Tehran and six big powers to curb Iran’s nuclear programme, officially lifted a ban on trading precious metals with Iranian state bodies. It also eased requirements to report trade in Iranian petrochemical products and the transport of Iranian crude oil and petroleum products.

While unlikely to have more than immediate symbolic impact, the steps could help Swiss companies aiming to do more business with Iran to respond quickly if and when the U.S. and Europe remove their own sanctions.

The sanctions lifted on Thursday had already been suspended by Switzerland since January 2014, but Swiss companies remain subject to the U.S. and EU restrictions.

“The latest move means that when they are eventually lifted, Swiss companies will be able to act immediately,” said Olivier Jakob, oil analyst at the Petromatrix consultancy in Zug, Switzerland.

“It puts Swiss companies and companies based here in the starting blocks.”

The commodities sector is important to the Swiss economy, comprising 500 companies that contribute 20 billion Swiss francs ($20.5 billion), or 3.5 percent, of gross domestic product.

Trading houses including Glencore Plc, Trafigura Beheer BV and Vitol Group employ between 10,000 and 12,000 staff.

Traders did not expect an immediate payoff since transactions are done in dollars and financed by banks that are unlikely to participate in Iranian trades so long as U.S. and EU sanctions remain.

“I don’t think anyone would like to risk bypassing world sanctions by going through the Swiss,” one trader said.

The government said its move was aimed at promoting “a broad political and economic exchange with Iran” but would monitor the nuclear deal, should problems arise.

The deal Iran struck last month with China, Russia, the United States, Germany, France and Britain aims to rein in Iran’s nuclear programme in return for relief from U.N., EU and U.S. sanctions that have hurt the Islamic republic’s economy. ($1 = 0.9749 Swiss francs) (Reporting by John Miller and Michael Shields in Zurich and by Dmitry Zhdannikov, Ron Bousso and Christopher Johnson in London; Editing by Keith Weir)