Singapore's Land Transport Authority said in an advisory to local motorists early Friday that heavy traffic was due to a protest "against (an) increase in Malaysian toll fees by Malaysian bus drivers".

Images on social media showed dozens of Malaysia-registered buses used for ferrying workers and students into Singapore standing stationary at the Johor Bharu city checkpoint in southern Malaysia.

Huge crowds of stranded commuters waited for the strike to end while some were seen walking across the one-kilometre (half-mile) causeway, one of two land crossings between the neighbours.

An AFP photographer at the scene said buses started moving at around 0200 GMT after at least two hours of standstill, although the heavy jams showed little signs of abating after that.

Malaysian media reports said bus drivers were persuaded to end their strike after local authorities promised a review of increased toll rates within a week.

Starting Friday, buses will have to pay a toll of 13.30 Malaysian ringgit ($4.15) at the Johor Bharu checkpoint in Malaysia for a round trip, a more than five-fold increase from the current 2.30 ringgit.

The increase will affect all motorists, including owners of private cars, who will now have to pay 16.50 ringgit from 2.90 ringgit for a round trip.

Malaysia announced the increase shortly after a July 1 announcement by Singapore that it will raise a permit fee for foreign vehicles from Sg$20 ($16) a day to Sg$35.

The increases have generated widespread consternation among both Malaysians and Singaporeans.

Over 310,000 commuters travel between Singapore and Malaysia daily through the two land crossings, according to the Malaysian government.

Singaporeans frequent Johor Bharu on weekends for tourism, dining and grocery shopping.

Around 200,000 Malaysians work in Singapore, mostly in factories and in the services sector. A number of Malaysian students also commute to Singapore daily from Johor Bahru.