A group of 19 British tourists remains missing in the Chinese region devastated by a massive earthquake this week, the Foreign Office and a travel company said on Wednesday.

The holidaymakers were travelling by coach on Monday from Chengdu to Wolong in Wenchuan county in Sichuan province when the 7.9-magnitude earthquake struck. They were accompanied by a local guide and driver.

"We are doing everything we can to know where these 19 Britons are," a Foreign Office spokesperson told AFP, while adding that there were no confirmed British casualties from the quake.

The tourists were clients of Travel Collection, part of the Kuoni holiday company, a spokesperson for whom said: "All lines of communication to the region are down and as such no further information is known at this time.

"We are working closely with the British Consulate in China," he added.

The comments came as the death toll rose to well over 20 000, as the full horror of the devastating earthquake began to emerge, with rescuers discovering whole towns all but wiped off the map.

The destruction around the epicentre in remote Wenchuan county is massive, with whole mountainsides sheared off, highways ripped apart and building after building levelled.

AFP