A prestigious British debating society said on Wednesday it had cancelled a speech by Sri Lanka`s president Mahinda Rajapaksa after planned protests against his visit raised security concerns.

Tamil groups in Britain and their supporters planned a big demonstration in Oxford on Thursday to coincide with Rajapaksa`s talk at the Oxford Union.

They were due to protest alleged human rights abuses during Sri Lanka`s threedecade war against Tamil separatist rebels, won by the army last year.

`Due to security concerns surrounding Rajapaksa`s visit which have recently been brought to our attention by the police, the Union has regretfully found that the talk is no longer practicable and has had to cancel his address,` Oxford Union said on its website.

It said that `due to the sheer scale of the expected protests, we do not feel that the talk can reasonably and safely go ahead as planned`.

Sri Lanka`s government said the Oxford Union leaders had shown they were `incapable of living up to the laudable standards of those who went before them in upholding their belief in the freedom of speech`.

The statement claimed that remnants of the LTTE had pressured the union to cancel the event, `regrettably supported by a handful of the foreign media`.