US Secretary of State Rex Tillerson said Tuesday that Washington will not interfere in Britain's negotiations to leave the European Union but urged both sides to resolve the matter quickly.

"The United States will maintain our longstanding special relationship with the United Kingdom, but at the same time we will maintain a strong relationship with the EU regardless of the outcome of Brexit," he said.

"We will not attempt to influence the negotiations but we urge the EU and UK to move this process forward swiftly and without unnecessary acrimony," he said.