Police are searching for a man who caused commuter chaos with a suspicious device at a train station this morning.

The man, aged in his 30s, was spotted leaving a Craigieburn train at North Melbourne station about 6am, police said.

It is believed he dropped a package with the appearance of an explosive device on the platform, before fleeing on a green scooter.

Police are searching for the man pictured (left), believed to be responsible for dumping a suspicious device which sparked commuter chaos. (Victoria Police/ Supplied via Phil Ridout) (Victoria Police/Supplied)

The man fled the scene on a green motorised scooter. (Victoria Police) (9news)

The station was evacuated and replacement buses were brought in after the shutdown in the middle of peak hour, causing massive delays.

Bomb Responsive Unit officers were called to the scene, and deemed the device safe.

Detectives are now searching for the man, who is described as having short dark hair, facial hair and an olive complexion.

He was wearing a broad-brimmed hat, black coat, tan pants and black boots at the time of the incident.

Trains are now moving normally again.

Commuters took to social media, capturing photos of the massive queues at train platforms across the city.

Meanwhile, Uber cashed in on desperate commuters looking for another way to work, with surge pricing coming into effect.

The Herald Sun reports an 11-minute trip from North Melbourne to Flinders Station skyrocketed to $90.