A little over two weeks out from polling day in Malaysia and tensions with its neighbour over the causeway have been cranked up with the Malaysian Election Commission (EC) urging the Singapore Government to do more to stop expats returning to vote in foreign vehicles.

In an attempt to address the car pooling being planned in the city state ahead of polling day, authorities said Malaysians coming home to vote on May 5 can only cross in a Malaysian-registered vehicle.

Pic: Jom Balik Undi Malaysia

It also urged Singapore’s Foreign Ministry to investigate reports that registered private vehicles were being used to send Malaysian voters home to vote.

Malaysia’s ruling Barisan Nasional (BN) coalition is facing its stiffest challenge in its six decades in government after losing a third of its Parliamentary seats in the last election.

Fears about the issuing of absentee ballots has led to the hundreds of thousands of Malaysian expats in Singapore opting to cross into Malaysia by car, bus and or on foot in order to cast their votes.

(READ MORE: Air, land or sea: Malaysian expats plan election exodus)

On Wednesday Singapore’s Foreign Affairs Ministry received a ‘memorandum’ regarding a Singapore-registered car in the Malaysian state of Johor, which had logos supporting the campaign of a political party in Malaysia.

According to reports in local newspapers, EC deputy chair Dato Wan Ahmad said: “Singapore authorities should also investigate if Singapore cars are used to help in the Malaysian general election. I believe Singapore Government likewise does not want to see cars from the neighbouring countries involved in its own general election. There should be mutual respect and sensitivity with each other.”

A number of campaigns have been urging overseas Malaysians to return home to vote. Bersih Singapore, a Singapore-based activist group, set up a car pooling service with a website matching Malaysian drivers with Malaysian passengers online.

Ahmad said that if passengers are Malaysian and they are travelling in vehicles hired by Malaysians they would be fine, but he advised the Singapore Government to investigate the identity of the car owners or the people hiring the vehicles “to avoid the issue of foreigners interfering in the internal politics”.

The EC also warned voters against waving campaign slogans, which is banned under Malaysia’s election laws. Slogans can’t be used after the end of the campaign period on the eve of polling day.

Vehicles transporting voters can only bear party flags but not campaign slogans or party labels, the EC said.

The EC’s warning is a sign of the high stakes of the 2013 election and the need to ensure that voting runs as smoothly as possible.