Malaysia's Chinese minority has for decades gone about its business and left leadership to a Malay-dominated regime, but in weekend polls they deserted it in what the premier called a "Chinese tsunami".

Prime Minister Najib Razak's term has since gone viral, touching off a debate over whether Sunday's bitter election battle presages a deepening divide between increasingly assertive urban Chinese and the country's majority Muslim Malays.

"Overall, the results show a trend of polarisation which worries the government," Najib said after declaring victory Monday, ruefully noting a "tsunami from the Chinese community."

Malaysia has enjoyed relative harmony among its main ethnicities for decades under the authoritarian template of the Barisan Nasional (National Front) coalition, but the mere mention of racial tension remains a sensitive issue.

The political and economic system is built on decades-old policies that prop up Malays to prevent dominance by the Chinese, who immigrated under British colonialism and control much of the economy despite making up just a quarter of the 28-million population.

The ruling United Malays National Organisation (UMNO), which has towered over Barisan and the country since independence in 1957, routinely refers to deadly 1969 racial riots as a warning against minorities threatening this status quo.

But minority Chinese and Indians increasingly reject their "second-class" status, egged on by an opposition that made its best showing ever Sunday.

"For the very first time in Malaysia's political history... the Chinese have decided to vote as a bloc and they have decided to vote the opposition," said James Chin, a lecturer with Monash University.

Chinese are angry about Barisan corruption and feel "marginalised", he said.

After an often racially divisive campaign by Barisan, which the opposition says was tainted by massive fraud, the regime largely held firm in the 222-seat parliament, retaining a solid majority as core rural Malay support held.

But several urban, Chinese-heavy seats tumbled to the three-party opposition, whose Chinese-dominated Democratic Action Party (DAP) was the alliance's big winner, gaining nine seats to end at 38.

The results were a snub to Najib, who reached out to minorities after a 2008 election setback with a much-touted racial-unity programme that is now in tatters.

It is considered imperative in Malaysia for government to project at least a facade of diversity, and Barisan's mix of 13 parties, several ethnic-based, were its claim to legitimacy.

But voters continued to desert its minority parties, which political analysts said increasingly reveals Barisan as a Malay camp under UMNO's thumb.

"We're lucky to still be in government at the federal level," said Saifuddin Abdullah, a Barisan reform voice who lost his seat Sunday, citing the "Chinese tsunami."

"There needs to be a new BN (Barisan)," he told online media, adding it was worrying that Barisan won with only a minority of the popular vote.

It held power thanks to a system of seat allocations that, critics say, unfairly favours Barisan strongholds.

But analysts said Najib faces an uphill task wooing back a Chinese community that UMNO has routinely made a bogeyman to shore up Malay support.

Opposition leader Anwar Ibrahim has for years called for reform of policies that give Malays advantages in business, education and home-buying, which he says are abused by a rich Malay elite.

Sensing the public mood, Najib also has promised some reforms.

But top opposition figure Lim Kit Siang, an ethnic Chinese who heads the DAP, said the country was set for deeper racial trouble if Najib does not fundamentally change the regime's ways.

"So long as he refuses to admit that, so long as he wants to polarise and racialise (the vote results), then they themselves are guilty of a racist outlook and they are incapable of any national reconciliation," he said.