President Nicolas Maduro has ordered paratroopers into the restive Venezuelan border city of San Cristobal amid fierce clashes between government forces and opposition protesters, as the leftist leader warned the US to stay out of the country's growing unrest.

The battalion was rushed in on Thursday night to "restore order" in San Cristobal, where Mr Maduro has threatened to impose martial law to quell the protests that began in the city two weeks ago and have since spread nationwide, claiming the lives of at least six people.