CANBERRA -- Australia's Prime Minister Kevin Rudd called for calm and Indian students led "vigilante" patrols on Wednesday after a second night of protests in the wake of attacks on foreign students in Sydney and Melbourne.

Scores of Indian students took to the streets of western Sydney, leading to two police arrests, after attacks in both Sydney and Melbourne which have sparked diplomatic protests and fears of an international student exodus from Australia.

"It's unacceptable for anyone to commit an act of violence against any student of any ethnicity anywhere in Australia," Rudd told local radio. "It's equally unacceptable for so-called reprisal attacks and for so-called vigilante action as well.

Rudd made his appeal after Indian students formed vigilante-like groups at train and bus stations in Melbourne following a string of attacks in the city over the past 18 months which Australian authorities insist have been crime-related.

Indian students believe the attacks have been "racist", warning of a culture of "curry bashings" in Australia, where foreign students are the country's third biggest export earner, worth more than $12 billion.

China last week joined India in raising concern about sporadic attacks on Chinese students in recent years, urging Australian authorities to ramp up security.

In a bid to ease tensions, police in Melbourne ordered groups of young Indian men patrolling three suburban railway stations at St Albans, Thomastown and Springvale to disband after they gathered to prevent more attacks on their countrymen.

In Sydney, around 70 people gathered in the western suburb of Harris Park, where Indian community representatives claimed to have been attacked by ethnic Lebanese-Australian gangs, responding with baseball bats.

Police have warned that Harris Park is a dangerous area at night due to criminal gangs and that the attacks on Indian students were purely opportunistic.

Indian community leaders have urged students to stay away from protest gatherings to avoid stoking tensions.

Australia's Foreign Minister Stephen Smith said it could take "some time" to bring the violence under control, while education experts have warned the damage to Australia's international reputation as a safe study destination could last even longer.

Police in Victoria state police said they were launching a fresh crackdown to restore order, building on increased patrols already announced. In Sydney, greater numbers of police also patrolled the worst-affected suburbs.

India's Prime Minister Manmohan Singh described the attacks in a speech to parliament as senseless violence, while Foreign Minister SM Krishna joined Rudd in calling for calm.