Upper Hutt's police station will be closed today after a diesel spill.

The station was evacuated about 6.30pm yesterday after diesel leaked from a generator in the basement, police said in a statement.

"The site will be cleaned and ventilated today before it can be reopened," they said.

Anyone in the Upper Hutt area needing help from police is advised to call 111 in an emergency and report non-emergency information to 105.

"We thank the public for their patience and understanding."