The problems as commuters rushed to work lasted two hours and affected eight stations on the new 36-kilometre (22-mile) section of the metro, including stops that opened only six months ago.
It came two days after the start of public hearings focusing on a massive disruption in December affecting 127,000 commuters, some stranded for hours underground in the worst breakdown since the metro was inaugurated in 1987.
A series of delays and problems have occurred with increasing regularity since, mostly blamed on mechanical or electrical faults. In the past week alone there have been four disruptions in different sections.
In the latest incident, problems emerged at around 8:05am, when train operator SMRT Corporation announced on Twitter that a track fault had led to a shutdown of services between four stations.
An hour later, SMRT said train services in eight stations were disrupted.
The Circle Line, where the problems occurred, cost in excess of US$6.40 billion and a decade to build, according to local media.
"The frequency of the breakdowns is really alarming," Shanta Arul, a 24-year-old corporate communications officer, told AFP.
"The main concern here is that it is a brand-new line. The other breakdowns were on the other older lines but this is new, so it raises questions on maintenance and the quality of equipment and trains they are using."
Another commuter, Evonne Tay, wrote on Facebook that she had switched to buses because train breakdowns were happening too frequently.
The metro was once regarded as one of Asia's best but its image has suffered because of breakdowns blamed by Singaporeans on mismanagement and overcrowding due to a spike in the intake of foreign workers and immigrants in recent years.
The train system, which includes underground and overhead sections, registered an average 2.41 million passenger trips per day in 2011, according to local media. Official figures were not immediately available.
The train network is split between two operators, SMRT and ComfortDelGro, which also run bus and taxi services.