US diplomats were taken off a train near the site of a mysterious military testing accident because they didn't have permits to be in the area.

The diplomats were let go, but Russia says it considers them to have broken the law.

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MOSCOW (Reuters) - Russia removed three US diplomats from a train near the site of a mysterious military testing accident on Monday because they did not have special permits to be in the area, the Interfax news agency reported on Wednesday.

Russia's state nuclear agency, Rosatom, has acknowledged that five of its nuclear workers were killed in an August 8 explosion during a rocket engine test near the White Sea in far northern Russia.

Interfax cited a source as saying that the US diplomats had been let go but are regarded to have broken Russian law.

In a report presented to the UN General Assembly this month, the US State Department said the nuclear accident near Nyonoksa, Russia, was caused by a nuclear reaction that occurred while Russians were attempting to recover a nuclear-powered cruise missile submerged in the White Sea after a failed test last year.

(Reporting by Andrey Ostroukh; Editing by Andrew Osborn)