Optus, Australia's second-largest telecommunications carrier, says the there has been limited impact to the Optus mobile network in the flood affected areas of Queensland as of 4pm today.

However, as the flooding situation is changing rapidly, some mobile sites are at risk due to power outages, according to an Optus spokesperson.

"Where possible, we have deployed backup generators in some locations throughout the flood affected areas to allow us to respond to power outages.

"Optus engineers continue to closely monitor the network during this period of excessive flooding in Queensland to minimise any impact on our customers."

In Toowoomba and the surrounding area, Optus has three mobile towers at Helidon, Gatton and Gunters Hill that are currently without power. However voice and data services are still available as coverage to these towns is being supplemented by additional towers in the area.

While Optus' equipment at the Toowoomba exchange has not been affected, residential and business customers may experience a disruption to fixed services due to flood damage within their premises.

In Brisbane, Optus currently has minimal disruption to its mobile and fixed network infrastructure.

However there is some congestion on the mobile network due to the high rate of calls within and surrounding the Brisbane CBD.

Optus said due to a loss of power within Mt Stradbroke, mobile towers within the Lockyer Valley are currently running on battery power.

"Due to the extreme flooding situation we are unable to access the area to install portable generators.

"It is likely that there will be a loss of mobile service to Optus customers within this area from this evening until we are able to deploy power generators onsite.

The telco said it continues to monitor the situation closely.