Two Malaysian men who allegedly tried to smuggle an Indian illegal immigrant out of Singapore in the boot of a car have been arrested by the Immigration and Checkpoints Authority.

They were trying to leave Singapore in a Malaysian-registered car through Woodlands Checkpoint on Thursday afternoon, when officers caught them.

The men, aged 21 and 22, were spotted behaving nervously as the officers examined the car. Their 34-year-old "passenger" was then found crouching and perspiring profusely in the modified car boot, and was also arrested.

The car has been detained and is liable for forfeiture.

Under the Immigration Act, the penalties for overstaying or illegal entry are a jail term of up to six months and at least three strokes of the cane, while the penalties for illegal departure is a fine of up to $2,000, a jail term of up to six months, or both.