WASHINGTON (REUTERS) - The Obama administration declared victory on Sunday in its effort to get HealthCare.gov working smoothly for the vast majority of users, saying the site had reached a goal of handling 50,000 simultaneous users after a five-week "tech surge."

In a six-page progress and performance report, administration officials said the troubled website could now handle at least 800,000 visitors per day, with the system remaining up at least 90 per cent of the time.

The new performance levels mark significant improvement after the Obamacare website's disastrous Oct 1 launch, when it crashed in the face of high traffic volumes and remained down 60 percent of the time for weeks.

But officials remain concerned about high volumes this month, with the potential for large numbers of people entering the site to apply for insurance coverage beginning Jan 1.