Darwin military base on heightened alert as Russian bombers trained nearby

A Darwin military base was put on high alert earlier this month amid fears Russian bombers conducting training exercises out of Indonesia were gathering Australian intelligence.

Military personnel at RAAF Base Darwin were operating at "increased readiness" as Russian strategic bombers – including two nuclear capable Tu-95s – stopped over at Indonesia's Biak Airbase for five days from December 4, the ABC reported.

At least 110 troops were deployed, with the Russian Ministry of Defence claiming they were performing an eight-hour "air alert mission over neutral waters of south Pacific Ocean".

Australia's Defence Department said the base was not in lockdown but an "appropriate level of readiness and posture" was employed.

"There was a brief period of increased readiness," a spokesperson told the ABC.

It said there were no instances of "unalerted or unscheduled foreign aircraft operating in Australian airspace during this period".

Leading defence expert Peter Jennings said he was not surprised about the heightened security as the long-range aircrafts are capable of collecting potentially damaging intelligence.

"I'm sure there would have been concerns about Russian intelligence gathering because they wouldn't have come this far south without wanting to look at the one significant [United States] allied presence in this part of the world, which operates out of [RAAF Base] Darwin and RAAF Base Tindall a little further south," the executive director of the Australian Strategic Policy Institute told the ABC.