"FMM expresses its concern that such actions are detrimental to freedom of expression and further erode media freedom in Sri Lanka."
It said that on Wednesday security forces prevented photo journalists from taking photos of a military truck transporting ammunitions which had met with an accident in a suburb of Colombo.
"Security forces even banned using mobile phones at the scene," the statement said.
"A camera belonging to Berty Mendis, a photographer at The Sunday Times, was taken and its film exposed, destroying all his photos."
In a previous incident, security forces forced journalists to leave the scene of an agitation by citizens in front of the UN office in northern Jaffna.
The people had gathered to meet UN Human Rights Commissioner Louise Arbour during her visit to the Jaffna peninsula on October 12.
"Afterwards, th