Koala spotted on CCTV strolling across train platform in Sydney's south-west

A train station in Sydney has played host to an unexpected furry visitor.

An adorable koala was captured on CCTV cameras at Casula train station in Sydney's south-west enjoying a stroll across the empty platform.

The koala was seen crossing the platform before confidently marching beside tracks and heading up the stairs shortly before 4am on Friday.

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At one point, the marsupial teetered past the yellow line and dangerously close to the train tracks.

One traveller spotted the brave koala and filmed it as it nestled on a step heading down to the tracks.

A train guard also noticed the animal and alerted the security control centre at Transport for NSW.

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Trains were warned to slow down while passing Casula train station.

NSW Police Officers arrived about 4.30am and helped guide the koala away from the station and back to the bush.

Transport for NSW confirmed the "unbearably cute passenger" is now back home in the bush safe and sound.

It shared CCTV footage of the koala's adventure through the station.

Casula train station is located near bushland around Leacock Regional Park, where the koala likely emerged from.