LONDON (Reuters)—Euler Hermes, the world's No. 1 trade credit insurer, said it might restrict the cover it provides to exporters doing business with Greece, citing fears the debt-laden nation could be forced out of the euro.

"Euler Hermes will most probably have to switch to a more prudent approach, also in the interests of customers," Euler Hermes Chief Executive Wilfried Verstraete said.

"Euler Hermes has maintained a high level of cover for its customers until today, but now we are confronted with a changing situation. The risk of Greece exiting the eurozone has been revived."

The company, majority-owned by Allianz S.E., Europe's biggest insurer, offers exporters worldwide protection against the risk of nonpayment. It insured deals worth €702 billion ($893 billion) last year.

Netherlands-based Atradius N.V., the second-biggest trade credit insurer, declined to comment on the terms it offers to customers but said it was carrying out an "in-depth" analysis of Greece's economic plight.

"The risk of Greek companies failing to pay their bills has increased substantially," a spokesman said.

Euler Hermes' Mr. Verstraete said the company would reach a decision on cover limits for Greece by the end of May.

Trade credit insurers advise customers on the creditworthiness of their counterparts as well as insuring their transactions.

They typically respond to increases in the risk of nonpayment by imposing lower limits on the value of the business they cover.

A Greek exit from the eurozone would force companies there to revert to the drachma, which would likely fall sharply against the single currency to reflect Greece's economic difficulties.

That would severely restrict Greek importers' ability to pay euro-denominated bills, potentially inflicting big losses on their overseas suppliers.

Greece imported €45.6 billion ($58.28 billion) worth of goods last year, more than double the €20.2 billion ($25.82 billion) it exported, according to International Monetary Fund figures.