A MAN in his mid-20s was paralysed today after crashing his bike into a tree in dense bushland in Sydney's south-west.

The Westpac Life Saver Helicopter said the man crashed his pushbike into a tree in bushland at Alfreds Point near Menai late today.

A crew had to be winched into the area to carry the man out on a stretcher.

A helicopter spokesman said the man was paralysed from the chest down and was being airlifted to St George Hospital.