Former prime minister Kevin Rudd's visit to Russia has no connection with events in Ukraine, his office says.
The West Australian newspaper reports Mr Rudd arrived in Moscow on Monday to meet President Vladimir Putin's top foreign affairs officials.
It cited unnamed Australian diplomats of suspecting Mr Rudd was attempting to "deal himself" into the crisis, which threatens a Cold War-style stand-off over the ex-Soviet state between Russia and G7 powers.
But a spokeswoman said the visit was linked to Mr Rudd's new role as a senior fellow at Harvard University's Kennedy school and a related research project on China.
"Mr Rudd is meeting with think tanks and other officials in Europe including the UK and Russia on this and broader foreign policy interests," she said.
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"This travel was planned more than a month ago and is not connected with recent developments in the Ukraine."
Foreign Minister Julie Bishop has issued updated advice for Ukraine, urging Australians to reconsider travelling there.
It comes after the government's warning earlier this week not to travel to the Crimea.
Ukraine's West-leaning government has accused Russia of staging a de-facto invasion by deploying troops in Ukraine's Crimean peninsula.
But Moscow insists it may be forced to protect ethnic Russians in Ukraine amid unrest following an uprising against fugitive former Ukraine president Viktor Yanukovych.
A former Labor colleague, Richard Marles, said Mr Rudd had booked the trip to Russia some time ago.
"As we all know, Kevin is a man who wants to keep abreast of world affairs," he told ABC radio.
"I'm not sure Kevin is putting himself in the position of trying to broker peace there."
Deputy Prime Minister Warren Truss was surprised by the report but supposed Mr Rudd had good intentions.
"I don't think Kevin Rudd's ever been short of ambition," he told reporters in Canberra on Wednesday.
Labor leader Bill Shorten said he couldn't shed any light on Mr Rudd's trip.
