[Photo/Screenshot of British Prime Minister Boris Johnson's Tweet]

A major incident has been declared following the derailment of a passenger train near Stonehaven in Aberdeenshire, Scotland.

At least one person is feared to have died, according to PA news agency.

Pictures posted on social media showed smoke billowing behind trees from the area and a number of ambulances and emergency services at the scene.

British Transport Police said officers were called to the scene at 9:43 am and remain there alongside paramedics and the fire brigade.

Scotland's First Minister Nicola Sturgeon described the incident as "extremely serious".

"I've had an initial report from Network Rail and the emergency services and am being kept updated. All my thoughts are with those involved," Sturgeon wrote on social media.

The incident took place amid severe flooding across Aberdeenshire caused by torrential rain and thunderstorms.

Mick Lynch, senior assistant general secretary at transport trade union RMT, said: "Our priority at this time is to support our members, their colleagues and their families and to do all that we can to assist the rescue operation which RMT members are currently involved in."

"The facts behind this ‎incident will need to be established in due course but at this stage we are focused on support and assistance and our thoughts are with all those impacted by this tragedy."