Boris Johnson is to face calls to slap targeted sanctions on the Southeast Asian nation amid its worst human rights crisis in two years.

Mu Sochua, 63, deputy leader of the opposition Cambodia National Rescue Party (CNRP), fled her homeland in early October after being publicly denounced by Prime Minister Hun Sen as an “urban terrorist”.

She will visit the UK in November to urge the Foreign Secretary to take action.

Cambodia, visited by about 159,000 Brits every year, and known for its stunning Angkor Wat temple complex, is spiralling towards dictatorship after CNRP leader, Kem Sokha, was jailed in September and independent media forced to close.