Snatch thieves preyed on two elderly women on Monday.

In the first incident, a gold chain worth $4,000 was snatched from an 84-year-old woman as she was watering plants in the common corridor outside her flat in Block 119 Serangoon North Avenue 1.

The woman felt a tug at the back of her neck and realised that somebody was trying to pull her necklace.

She put up a struggle but the thief managed to lift the chain from over her head and fled.

The woman's 18-year-old grandson came out of the flat and gave chase.

He caught up with the suspect at Block 124 and struggled with the culprit. But the suspect managed to get away.

The suspect is described as dark-complexioned, in his 20s and about 1.7m tall. He is said to be stocky, with messy hair and was wearing a white polo tee-shirt and beige-coloured shorts.

The second case happened at Block 533, Woodlands Drive where a 73-year-old woman was on her way up to her flat at about 2pm.

She entered a lift and just before the doors closed, a man squeezed inside and stood next to her.

He pressed the button for the third floor.

When the lift reached the third floor, the man walked out but just as he left, snatched the woman's handbag and fled.

He was described as dark complexioned, in his 30s, slim and about 1.7m tall. He had short black hair, and was wearing a white tee-shirt with long, black pants.

The handbag, worth $90, contained an ez-link card valued at $20, a mobile phone, and $150 in cash.

Police are appealing for witnesses.