The call came in response to increasing attacks on and intimidation of journalists critical of the government and the military.
"Media freedom is an essential feature of a vibrant democracy," the statement by the political parties said.
"An independent and professional media able to function without interference or influence from government and other partisan influences and exists for the social, political, cultural and economic betterment of polity and society is an integral part of democratic governance."
However, it said, independent media and journalists in Sri Lanka today are terrorized through a spate of killings, abductions, assaults, arbitrary arrests and detentions.
"They are subject to violence, both physical and verbal, to a degree that is unprecedented."
The pol