Mystery boat docks at Geraldton

A suspicious boat that docked at Geraldton on WA's mid-west coast was not carrying asylum seekers, Australian Border Force has confirmed.

Local website Everything Geraldton reported up to six men who were on board had been detained and were being questioned.

An Australian Border Force spokeswoman told AAP the boat was not an irregular maritime arrival and Monday's investigation was part of an ongoing operation involving Commonwealth and state authorities.

"As operational activity is ongoing, it would not be appropriate to comment further," a WA Police spokeswoman said in a statement.