Fresh racial and religious rows have marred celebrations to mark Merdeka Day as Prime Minister Najib Razak made a plea for unity.

Najib called on Malaysians to "repair the bridges and tear down the divisive walls" that exist between the races here even 52 years after nationhood and the end of colonial rule.

"Bear in mind that what we have now will not necessarily become better. On the contrary, we can lose it all if we are not careful," he said in his first National Day address since coming to power in April.

Najib has launched a 'One Malaysia' campaign to address barriers between the nation's ethnic groups.

The new premier is working to win back support from Malaysia's Chinese and Indian minorities, who swung towards the opposition in national elections last year that handed the ruling coalition its worst ever results.

Racial and religious rows continue to erupt, including an incident last Friday when Muslim protesters trampled on a severed cow's head in protest at the building of a Hindu temple.

Politicians from all sides condemned the explosive action, and police said they would launch an investigation over whether the act constituted sedition - an extremely serious charge.

However, the organisers were defiant, refusing to apologise and rejecting responsibility for the incident.

Hardening of intolerant attitudes

Veteran opposition lawmaker Lim Kit Siang said that racial politics had only increased in recent times, and that the 'One Malaysia' campaign had failed to unite the country.

"There is a further polarisation of race and religion, with the hardening of intolerant attitudes and stances, creating situations unseen or unheard of in the previous history of the nation," he said.

"Let all patriotic Malaysians of goodwill recognise the danger signals to our plural society."

Last month, the dramatic case of a Muslim model who was sentenced to be caned for drinking beer also highlighted concerns that the nation's secular status is under threat as Islamic law becomes more influential.

Kartika Sari Dewi Shukarno, 32, was arrested at a hotel nightclub and sentenced to six strokes of the cane, in a rare prosecution using religious laws that ban alcohol for Malaysia's majority Muslim Malays.

As concerns mounted that Malaysia's reputation as a moderate country was under threat, the authorities abruptly announced the case was to be reviewed and put the punishment on hold indefinitely.

- AFP