A man's been arrested after a baby was critically injured in Wairarapa last month

Police were notified when the baby arrived at Masterton Hospital seriously hurt on July 25, and was shortly after moved to Auckland's Starship Hospital.

A 22-year-old man's been charged with wounding with intent to cause grievous bodily harm and breaching a protection order.

It comes after a 23-year-old man was also charged this week for injuring a young baby in the Hutt Valley in June.

Police say they'll continue to relentlessly pursue anyone who commits heinous acts on vulnerable people.