Police are investigating the cause of the blaze, which has been described as suspicious.
Images have shown flames rising above treetops in Xabia, south of Valencia.
Firefighters had reportedly believed the fire was under control, but new outbreaks have begun.
The area, which is popular with tourists, has seen high temperatures, which are expected to remain into next week.
Aircraft is now being used to try and tackle the fires.
Forest fire near Benidorm leads to evacuations
Register for free to continue reading
Get unlimited access to the latest travel industry news and analysis, comment on articles and sign up to newsletters.
Register for free
Already registered? Login here or below.
Having difficulty logging in? Try these tips, or contact support@flymy.co.uk