Labelling the road charge scheme "discriminatory", Singapore's Ministry of Transport said it is biased against Singapore-registered vehicles, as the fee is applied only at Malaysia's checkpoints with Singapore.

"We will match it in some form," the ministry said in a statement Monday evening, adding that details will be announced in due course.

From 12.01 a.m. Monday, those driving Singapore-registered cars to Johor Baru - either by the Causeway or Second Link - were charged an additional RM20 fee, on top of the checkpoint tolls imposed by both countries.

With the new road charge, a round trip for a Singapore car going into Johor will incur about $19 in tolls and fees.

Government and commercial vehicles, including those for public transportation, are exempted, however.

Malaysian Transport Minister Liow Tiong Lai defended the scheme last Saturday, insisting that it was not discriminatory.

"We will impose the road charge not only at our border with Singapore, but also our borders with Thailand, Brunei and Indonesia with a similar charge of RM20 per car," he was quoted as saying in a Bernama news report.

Besides Singapore, Malaysia also shares 10 other road entry checkpoints with Thailand, Brunei and Indonesia. The Malaysian Transport Ministry told The Straits Times that plans to levy a road charge at these other checkpoints are in the "pipeline" and an announcement will be made closer to the launch date.

Singapore's matching of the road charge would add to costs for drivers of Malaysian cars entering the Republic. Besides checkpoint tolls, drivers of foreign-registered cars are required to pay Vehicle Entry Permit (VEP) fees for each day the cars are kept or used in Singapore.

In general, a fee of $35 per day applies for cars between 2 a.m. and 5 .p.m, Mondays to Fridays. But motorists also get 10 VEP-free days each year.