Russian warships approaching Australia from the north have been brushed aside as a mere show of strength ahead of the G20 summit in Brisbane this weekend. (The picture above is a dated one showing joint naval exercises by China and Russia earlier this year.) REUTERS

Australia is on alert, but not unduly perturbed by four Russian warships approaching its waters.

In what is being seen as a mere show of strength by Russian President Vladimir Putin ahead of the G20 summit in Brisbane, the Australian Defence Force (ADF) did not perceive any major threat as the warships were in international waters, reports BBC.

Two frigates and a surveillance aircraft are tracking the ships.

Russian naval vessels have been deployed earlier too during international summits, including the Apec summit in Singapore in 2009, the ADF noted.

Analysts however note that the warships' movement comes just after a Russian missile cruiser conducted unilateral live-fire drills in the South China Sea, indicating a "flexing of muscles."

Recent talks between the two countries had included the downing of the Malaysian airliner by Ukraine rebels, backed by the Kremlin. Australia has not minced words in tracing the act to Russia's door.

Putin has maintained a stoic denial.