Anne Heche is in "extreme critical condition" after the actor was hospitalised last week with severe burn injuries following a car crash, according to her representative.

The Emmy-nominated actor continues to be in a coma, the representative said in a statement to entertainment outlet Deadline.

"At this time Anne is in extreme critical condition. She has a significant pulmonary injury requiring mechanical ventilation and burns that require surgical intervention. She is in a coma and has not regained consciousness since shortly after the accident," the representative said.

The updated statement comes days after Heche's publicist released a hopeful statement Saturday citing her as being "in stable condition".

The 53-year-old actor, known for the soap opera "Another World" and films such as "I Know What You Did Last Summer" and "Six Days, Seven Nights", has been in the hospital since Friday when a car she was driving crashed into a residential building and caught fire in the Mar Vista area of Los Angeles.

There has been a lot of chatter about Heche's condition preceding the crash as she was filmed driving erratically and speeding in the minutes prior to the accident, including getting into another, minor car accident, blocks away from the crash site.

A podcast featuring Heche, in which she is heard slurring her speech, was released Friday, and has been linked to the crash on social media.

Sources close to the Los Angeles Police Department told entertainment website TMZ that the actor may have been driving under the influence of drugs and/or alcohol.

Authorities have obtained a warrant to draw Heche's blood, the insiders said.

Neighbours of Lynne Mishele, whose home was destroyed in the crash, have raised over USD 75,000 as of Monday afternoon via a crowdfunding page to help her get back on her feet.

According to the page, Mishele "very narrowly escaped physical harm" in the accident, but she lost "her entire lifetime of possessions".