KYIV (REUTERS) - An American woman working at the U.S. embassy in Ukraine's capital Kyiv died after a suspected assault in a park near the mission, authorities said, and a search was underway for the possible perpetrator.

Ukrainian police said a passerby found the woman unconscious with a head injury, wearing running gear and headphones in the area of western Kyiv. She was taken to hospital, where she died.

Police added they were seeking a dark-haired man aged between 30-40, who wore dark shorts and a T-shirt, and may have been involved in beating the American woman.

In a statement, the US embassy, which employs about 181 Americans and more than 560 locals, said it was working with Ukrainian authorities to determine what happened.

The woman's identity and job were not given.

Interior Ministry spokesman Artem Shevchenko posted pictures of the scene on Facebook, showing the woman had been found by railway tracks next to a wooded area.

"The National Police of Ukraine is investigating her death as a deliberate murder ... but an accidental death is not ruled out. The body was in sports clothes and wearing headphones," he said in a statement.

The Ukrainian ambassador to Washington, Volodymyr Yelchenko, urged quick resolution and prosecution.