by Razak Ahmad and David Chance

TAIPING, MALAYSIA - Voters turned out in large numbers on Tuesday in a tense by-election in the northern Malaysian state of Perak that is seen as a key test for the country's new prime minister.

Amid a heavy police presence and soaring temperatures hundreds of supporters of the government and opposition faced off outside a polling station in this rural Malaysian constituency where a parliamentary seat is being contested.

The seat in Perak which is being contested along with two state assembly posts is especially tense as new Prime Minister Najib Razak led a putsch to oust the opposition-led state government.

'This by-election is not just about progress and promises of development but also about larger issues such as justice and corruption,' Ilham Abdul Aziz, a 32-year old businessman, who had just cast his vote.

By 1215pm, turnout in the Perak constituency was 20 per cent, while in the state assembly seat in neighbouring Kedah, it was 42 per cent and in a state seat in Sarawak on the island of Borneo it was 70 per cent, according to the Election Commission.

About 100,000 voters are eligible to vote in the three state seats, representing a major test for Najib just four days after he became prime minister.

The election results will not alter the national balance of power but analysts say Najib needs to win to put his stamp on the government and reverse a growing tide of public disappointment in the ruling coalition.

'If the (ruling coalition) BN or (opposition) Pakatan were to win 3-0 tonight, a mini-tsunami could inundate the political landscape,' the pro-government New Straits Times newspaper said on Tuesday.

The ruling National Front coalition has lost two crucial by-elections since last August, after suffering its worst performance in the 2008 general election.

One of the by-elections returned opposition leader Anwar Ibrahim to parliament.

Analysts say the ruling coalition stands a good chance of winning the Batang Ai state seat in Sarawak but faces a tough fight for the other two seats.

The National Front coalition, backed by influential former premier Mahathir Mohamad, has promised economic reforms as Malaysia faces its worst recession since the Asian financial crisis a decade ago.

But Najib who took over from ex-premier Abdullah Ahmad Badawi last Friday also has his hands full to attempt to convince voters that he can clean up the National Front and the main coalition party that he leads, the United Malays National Organisation.