BERLIN, May 14 (Xinhua) -- German entrepreneurs expressed great concern about their deals in Iran after U.S. President Donald Trump announced the decision to withdraw from the historical nuclear deal sealed in 2015 and to reinstate sanctions against Iran.

"We will now very carefully analyze the sanction-related steps announced by the United States," German conglomerate company Siemens AG said in a statement on Monday.

The Munich-based and largest industrial manufacturing company in Europe signed a contract in October 2016 to upgrade Iran's railway network and supply components for 50 diesel-electric locomotives to Iran.

Siemens said it will comply with all the export controls that may emerge.

Its chief executive Joe Kaeser said in an interview with CNN on Sunday that according to his understanding, Siemens could not do any new business in Iran, or else it could face sanctions from the United States.

Siemens's concerns were widely shared by other German companies that are active in or with Iran.

German carmaker Volkswagen(VW), which resumed its exports to Iran in 2017, said it was closely monitoring and reviewing the political and economic development in the region.

Another German automaker Daimler AG also said it would analyze the impact of the U.S. decision on its business in Iran.

Uncertainties about the legal consequences of U.S. exit from the nuclear deal dominate German businesses, Eric Schweitzer, president of the Association of German Chambers of Commerce and Industry, said on Monday.

There is fear that financial institutions would withdraw from businesses in Iran, eying the threatening sanctions by the United States, Schweitzer warned, saying it would leave further financing of deals in question.

He called on the German government and the European Union to look after its businesses operating in Iran by limiting direct damage and ensuring fulfillment of existing contracts.

According to official figures, exported German goods to Iran increased by around 400 million euros (476 million U.S. dollars) to a total of 3 billion euros (3.57 billion dollars) in 2017. German-Iranian commerce soared by 42 percent since sanctions were loosened in 2016, gradually returning to levels between 2000 and 2010.

White House national security adviser John Bolton told the press on Sunday that "it's possible" that European companies doing business with Iran would be subject to sanctions.