Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the man was located at a Markham Street property in Heywood about 1pm.

He entered a man hole and then climbed onto a house roof while police officers surrounded the property.

The wanted man eventually jumped four metres down to the ground after negotiations and fled on foot, but was chased down by a police officer and arrested.

He will be interviewed today and is expected to be charged with a range of offences.

The accused man is likely to be remanded in custody overnight to appear in the Warrnambool Magistrates Court on Thursday for a bail/remand hearing.

Four warrants had been issued for the 20-year-old's arrest in relation to breaching court orders, assault and drink driving related matters.

Police will allege he was the driver of a Holden Jackaroo which rammed an unmarked police vehicle in Portland on Tuesday afternoon, which sparked a manhunt.

No officers were injured in the ramming, but damage to the front-end of the police vehicle is expected to run into the tens of thousands of dollars.

"It's very pleasing to have this gentleman in custody," Detective Sergeant von Tunk said.

At 11.55am: Police are appealing for public assistance to help locate a Portland man.

Four warrants have been issued for the 20-year-old's arrest in relation to breaching court orders, assault and drink driving related matters.

He was described as Caucasian, about 170cm tall with a thin build and short brown hair.

He was believed to be travelling in a heavily damaged dark coloured Holden Jackaroo.

Anyone who sights the vehicle was urged to contact Crime Stoppers on 1800 333 000 or make a confidential report at www.crimestoppersvic.com.au

At 8.45am: The manhunt continues this morning for a 20-year-old driver who rammed an unmarked Portland police car on Tuesday afternoon.

Portland police are looking for and seeking information about a Holden Jackaroo which has been driven by the offender.

Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said the man was still wanted and believed to be in the Portland/Gorae area.

"South Australia police have also been alerted," he said.

"Anyone with information is requested to urgently contact the Portland police station or Crime Stoppers on 1800 333 000."

The 20-year-old driver rammed an unmarked police car in Portland's Daniel Street at 12.40pm as he escaped from detectives.

No one was injured.

The driver was later cornered at an address in Cape Nelson Road, but escaped again after smashing through a fence.

The offender then took refuge at an address in Beaugleholes Road at Gorae but fled before police arrived.

More to come.

Tuesday evening: A manhunt is underway in Portland for a 20-year-old driver after he rammed an unmarked police car on Tuesday afternoon.

Detective Sergeant Jason von Tunk, of the Portland police crime investigation unit, said a wanted 20-year-old man rammed an unmarked police car in Portland's Daniel Street at 12.40pm.

"We just got rammed by a wanted person driving a Holden Jackaroo as he attempted to escape," he said.

"There were no injuries to detectives in the vehicle."

Detective Sergeant von Tunk said the wanted driver was later cornered at an address in Cape Nelson Road.

"But, the driver managed to decamp by smashing through a fence," he said.

"The male offender then took refuge at an address in Beaugleholes Road at Gorae but again decamped before police arrived.

"He is still wanted."

Anyone with information is requested to contact the Portland police station or Crime Stoppers on 1800 333 000.

Listen to the latest episode of our weekly episode The Booletin and Beyond:

Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.