The warning followed the second incident in two days where protesters used PWCS sites to highlight climate issues.

A number of protesters were discovered fastened to industrial equipment at PWCS' Carrington terminal.

PWCS general manager Graham Davidson said: "We respect the right to protest, but also warn that trespassing at dangerous industrial sites presents obvious risks to the safety and lives of protestors, PWCS employees and police."

"In this respect, the protest action is concerning and grossly irresponsible."

Davidson said PWCS would cooperate with police at all times when dealing with protestors.

The Newcastle Port Auhtority has confirmed shipping operations were not affected by protest activities at the port.