Unidentified gunmen shot dead an editor of a Tamil magazine in northern Sri Lanka, days after a top woman journalist said she received a death threat, the local Free Media Movement said on Friday.

Subash Chandraboas, 32, editor of the Tamil monthly Nilam, was gunned down late Monday at his residence in Vavuniya, 260 kilometres north of Colombo, the rights group said.

Chandraboas also freelanced for other publications including the London-based magazine Tamil World.

The FMM, which consists of journalists and rights activists, said it was 'appalled by this killing.'

'Although the reason for killing him is not clear, the FMM fears that this could be another attack on journalists and media personnel working in north and east,' it said in a statement.

The report on the killing comes after an editor from an English language national daily said she received a death threat from Sri Lanka's defence secretary Gotabhaya Rajapakse.

Rajapakse, who is also President Mahinda Rajapakse's brother, denied he threatened the editor. At least nine journalists and media workers have been killed in Sri Lanka in the past 16 months.