Brussels/IBNS: A Russian fighter jet on Tuesday dumped fuel on an American drone over the Black Sea then collided with it, causing the drone to crash, the US military said.

US European Command said two Russian Su-27 fighters intercepted the unmanned MQ-9 Reaper over international waters and one clipped its propeller.

"Several times before the collision, the Su-27s dumped fuel on and flew in front of the MQ-9 in a reckless, environmentally unsound and unprofessional manner," it said.

NATO diplomats in Brussels confirmed the incident, but said they did not expect it to immediately escalate into a further confrontation.