The Southeast Asian city-state, known for its efficient government, spectacular skyline and dozens of luxurious shopping centres, suffered three major subway disruptions last week, each lasting several hours.

On Thursday, hundreds of commuters were trapped underground without light and ventilation for over an hour before they heard from train operator SMRT (SMRT.SI).

The breakdown on the north-south line, which connects the north of the island to the city centre and serves the main Orchard Road shopping belt, caused huge traffic jams, with crowds spilling into the streets to try to find a way home.

Singapore, one of the world's most densely populated countries, discourages car ownership through hefty taxes, leaving most commuters to rely on the subway.

Lee has promised a full inquiry and the government regulator has stepped in to check trains and subway lines.

Lee's People's Action Party (PAP.L) has been in power since independence in 1965. It saw its share of vote dip to just over 60 percent -- its lowest share ever -- in May parliamentary elections with government accountability, inflation, big income gaps and an influx of foreign workers key issues among voters.

"A breakdown in train services is in itself no big deal. That happens all over the world. However, foreign investors are looking with great interest at how the government is dealing with an electorate that seems to demand more accountability," said Hans Vriens, the managing partner of a Singapore-based corporate advisory firm.

The incident also puts into spotlight on whether some of Singapore state companies are behind the times.

"SMRT with its twitter service from 9 a.m. to 5 p.m. clearly doesn't cut it," added Vriens, referring to the company's failure to use new media to disseminate information. He was on a train that broke down on Saturday morning.

Passengers complained that SMRT staff were slow to inform them, including those stuck on trains, about the disruptions and what was being done to help those who had been stranded.

The problems were made worse when several shuttle buses called in to ferry affected passengers were late, due in part to drivers losing their way, the Straits Times newspaper reported on Monday.

Several commentators called for the resignation of SMRT CEO Saw Phaik Hwa and over 1,400 people signed an online petition asking her to leave. Saw said she had no plans to quit.

Analysts expect the government to become more actively involved in overseeing the operations of public transport operators SMRT and ComfortDelGro (CMDG.SI), which in the short-term could hurt earnings.

TEMASEK LINK, SECURITY FEARS

Saw, who has been credited with trebling SMRT's net profit to S$161.1 million over the past eight years, had already been under fire for overcrowded trains and frequent breakdowns in the subway system.

The Workers' Party, the largest group in the opposition, which controls six of 87 seats in parliament, asked if the increasing breakdowns along two subway lines were the result of insufficient investment in maintenance and upgrades.

"If so, were the lack of essential investments a result of pressure on the public-listed MRT operators to minimise costs and maximise profits for the benefit of their shareholders, at the expense of the 2.3 million commuters?"

SMRT is a subsidiary of Singapore state investor Temasek , whose CEO Ho Ching is Lee's wife.

Other commentators voiced concerns about Singapore's ability to cope with civil emergencies, given the inadequate response by SMRT to the breakdowns when they first occurred.

"Imagine if the service disruption was caused by a terrorist attack and the panic, confusion, and fear multiplied many times," said Eugene Tan, an assistant professor of law at Singapore Management University.

He said part of the problem was due to SMRT staff not being given the authority to make decisions on the spot.

"Standard operating procedures did not work and SMRT staff seemed disempowered, awaiting instructions from higher up, to deal with the fluid situation," Tan said.

CIMB economist Song Seng Wun said the breakdowns, if not handled well, could be another flashpoint for politicians in the next election on top of other longstanding issues.

"Thrown into a first-time crisis like this, too many people just froze, while waiting around like a headless chicken looking for guidance," Song said.

"The handling of an unknown emergency is still somewhat lacking. It just illustrates that Singapore Inc doesn't respond well if there is no manual."

(additional reporting by Saeed Azhar and Cerelia Lim; Editing by Ron Popeski)

• A Permanent Economic Emergency