VIOLENT clashes between opposing ethnic groups living in Melbourne are tipped to become worse after angry mobs crossed paths in the city at the weekend, opinions Herald Sun.

Police have been asked to explain why they allowed two opposing groups with a history of violence to protest in the city at the same time.

YouTube footage shot near Parliament showed one car, part of a convoy of Australian Sri Lankan Tamil supporters, being attacked by Sinhalese protesters.

At least eight people were injured, two seriously, during the altercations.

The violence continued with at least four Sinhalese shop fronts damaged at Clayton.

Sinhalese spokesman Don Mahindapala said police should be held accountable for the violence.

"It is like putting petrol and fire together," he said.

He said Sinhalese leaders were "trying to keep a lid" on brewing tensions.

Police spokeswoman Melissa Seach said police didn't expect the rallies to cross paths.

Tamal Youth co-ordinator Haran Thanabal said it was likely they would be a target for violence as the protests continued.

Police on horseback were called in to protect more than 1000 Tamil protesters who marched from Spring St to Southbank yesterday.

They were protesting at Sri Lanka's reported use of chemical weapons.