GENEVA — Amid rising international tension over Ukraine, the United Nations’ refugee agency said Tuesday that the fighting there had displaced more than a million people and warned of “devastating consequences” if it did not end soon.

The number of people that the agency officially counts as displaced inside Ukraine has nearly doubled in the last three weeks, to 260,000, but the actual number is much higher because many of those fleeing are staying with families and friends, Adrian Edwards, a spokesman for the refugee agency, told reporters in Geneva.

Many more have been forced out of Ukraine, including around 814,000 people who Russia says have crossed the border since the start of the year. Tens of thousands of other Ukrainians have moved to other European countries to escape the conflict or left for vacations or family visits and opted not to return.

“It’s safe to say you now have over a million people displaced as a result of the crisis,” said Vincent Cochetel, director of the refugee agency’s European bureau.