Lisa Joanne Govan was 28 when she disappeared in suspicious circumstances from Kalgoorlie in 1999.

She was last seen on Boulder Road near the Foundry Hotel - close to the then Deroes bikie gang clubhouse in the West Australian town 600km to the east of Perth - in the early hours of October 8 that year.

Ms Govan never returned home.

Despite an extensive police investigation and nationwide media coverage, she is still missing and detectives believe she was murdered.

As part of the ongoing investigation, police are seeking to identify the current owner or location of a white 1985 Toyota Landcruiser tray back utility vehicle.

A similar vehicle arrived at the Deroes clubhouse on the morning of Lisa's disappearance, departed and later returned.

Police Minister Michelle Roberts says she hopes progress in the case might help Ms Govan's family find some closure.

"She had her whole life in front of her, she had a family that loved her, and for 21 years that family has suffered in silence," Ms Roberts said.

Homicide detectives from the Special Crime Squad recently reviewed Ms Govan's case, and requested an increase to the $250,000 reward for information.

The state government has agreed to offer a reward of up to $1 million for information that leads to the arrest and conviction of the person or people responsible for the suspected abduction and murder.

Detectives believe people in Kalgoorlie know what happened to Ms Govan, but so far they have not spoken up.

"Police never give up on cases like this one," Ms Roberts said.

Ms Roberts said police are prepared to provide protection for anyone who can help them crack the case.

Extra police officers are manning Crimestoppers phone lines on 1800 333 000 in the hope that people can provide fresh information.

Australian Associated Press