Tram passengers were startled and alarmed late last night when two men terrorised them by wielding a box cutter and a garden stake.

Police arrested the men after a series of armed robberies and thefts targeting passengers on the route 96 tram to St Kilda.

A police spokeswoman said three men were threatened with a garden stake and a box cutter and robbed during separate incidents on the tram.

But the alleged robbers' trip was terminated when they arrived at a Fitzroy Street stop at 11pm with police waiting for them.

Two men, a 22-year-old from St Albans and a 28-year-old from South Melbourne, were arrested. The spokeswoman said the men were assisting police with inquiries.