A woman has been rescued from the Abel Tasman National Park after becoming unwell during a day walk, police say.

The 64-year-old was with her partner in the park, at the top of the South Island west of Nelson, when she became unwell and could not walk any further.

Police, St John ambulance paramedics and search and rescue volunteers came to her aid in the Nelson Marlborough rescue helicopter, and a second team of search and rescue volunteers responded in the Tasman harbourmaster's boat to help.

The woman was found in bush two kilometres west of Anchorage Hut and flown to Nelson Hospital for treatment.