Image copyright AP Image caption Life-size image of protesters were projected on a screen in central Seoul

A holographic "ghost protest" has been held in South Korean capital Seoul against what the organisers say is the erosion of free speech in the country.

Dozens of demonstrators appeared on a big screen near the main gate of Seoul's historic Gyeongbokgung Palace.

Officials had earlier said the rally's application was submitted incorrectly, warning of a "stern response". But the event was peaceful.

The demonstration was organised by Amnesty International Korea.

Image copyright AP Image caption A number of people turned out to watch the unusual event, which passed peacefully

"Authorities are banning more and more public protests, especially in central Seoul, citing reasons like traffic jams or public inconvenience," Amnesty's Kim Hee-jin was quoted as saying by the AFP news agency.

"We wanted to show that the situation has become so restrictive that only ghosts like these may freely march on the street," she added.

The South Korean authorities have been recently been accused of using excessive force to disperse public protests and even banning rallies under the pretext that they cause traffic jams and inconvenience to local residents.

The government in Seoul has repeatedly denied such claims.