KIEV (REUTERS) - McDonald's has suspended work at its restaurants in Crimea for "manufacturing reasons", the US fast-food chain said on Friday, the second international company to cease operations this week on the peninsula annexed by Russia.

Crimea's hasty unification with Russia, which Ukraine and the West do not acknowledge, has worried companies with assets in the Black Sea region as it is unclear how the change may impact business.

McDonald's, which operates three restaurants in Crimea, said it hoped to resume work as soon as possible, but offered to help relocate staff to Ukraine, signalling it did not expect its Crimean business to reopen in the near future.

"The company has provided an opportunity to all employees ... to transfer to any other McDonald's restaurants in Ukraine preserving their positions, salaries and fees and paying to relocate employees and their families," it said in a statement.

The closures follow Geneva-based Universal Postal Deutsche Post's announcement that it was no longer accepting letters bound for Crimea as delivery to the region was no longer guaranteed.