A man has been charged with kidnapping and assault over two separate attacks against two women aged 74 and 60 in Sydney's south-west this month.

The 49-year-old man allegedly kidnapped a 74-year-old woman, after forcing his way into her house, on Tuesday February 4.

He knocked on the woman's door on Grant Close in Kemps Creek around 12.45pm, asking to use the phone, before he allegedly barged into the house when she offered assistance.

He allegedly demanded cash and took two gold necklaces, before demanding her keys and instructing her to get into her car.

He then drove her to various locations, before getting out of the car near Elizabeth Drive in Liverpool, leaving the keys in the car.