ACT police have extensively searched the East Basin, Molonglo River foreshore and around the bridge but have found no trace of the man who had driven to the lake, pursued by police, around 1.15am on Monday.

He man and his female companion jumped from their car and fled on foot when they reached the East Basin.

The woman was caught and arrested but the man jumped in the lake and began swimming away in the darkness. He was last seen about 100 metres from the shoreline.

Police refused to speculate on whether he had made it to shore, only commenting that they are "continuing to follow a number of enquiries and assessing available evidence".

"The investigation is ongoing," they said in a statement.

There were some police boats reported to be out and still patrolling the lake on Tuesday. Police divers were seen on Monday using grapples in the water, which would suggest they also feared the man had drowned.

The intense police search activity around the lake in the early hours of Monday, including the use of the Toll Southcare Rescue helicopter to scour the water surface from above, came after a car chase through Canberra suburbs.

A vehicle had failed to stop for police, and the driver had then evaded police before heading down to the lakeside. It is strongly suspected the man was involved in property crime offences and traffic-related matters.

Police confirmed in a previous statement that this incident was connected to the arrest in Hackett yesterday of two other women, one of whom got stuck in the window of a car as she attempted to get away and was then Tasered.

She, too, had been involved in a high-speed car chase through Canberra on Sunday night, reaching speeds of up to 140km/h.

Anyone who may have seen the man clambering out of the lake on Monday morning or has any other information which could assist police is urged to call Crime Stoppers at 1800 333 000.