Mobile operators here may be required to maintain two separate sets of core network equpiment to make sure that there are back-ups in case of an outage.

Minister for Communications and Information Yaacob Ibrahim revealed this in Parliament on Monday, while replying to questions tabled by MPs about last month's fire at a SingTel Internet exchange.

The Infocomm Development Authority (IDA) of Singapore is currently studying if the change can further improve the country's mobile network, after an in-depth review of mobile operators' network resiliency, after M1 suffered the worst mobile network failure for almost three days in January.

In the same way, Singapore's telecoms regulator is now looking into what caused the fire, that crippled essential services across Singapore.

Mr Yaacob said IDA's probe will focus on what caused the fire, whether it could have been avoided, if SingTel had done all it could to restore services quickly and provided alternatives for affected businesses, and what can be done to make sure a similar incident does not happen again.

Acknowledging that a resilient mobile network is important for the country, Mr Yacoob highlighted four components which he said were core to the concept - diversity, resistance, redundancy and recovery.

"Focusing on diversity alone does not make the network more resilient," he said in Parliament.

Singapore's two other telcos, M1 and StarHub, had also been brought down by the SingTel fire, leading some to ask if a separate Internet network would prevent such a major outage.

But Mr Yaacob said a second, fully diversified network would have to be completely separate from existing infrastructure, and would be more expensive to build than the Next Generation National Broadband Network.