Microsoft has admitted that it still has not fixed the problem which has left tens of millions of Hotmail users unable to access their e-mail accounts over the past two days.

Access to all of Microsoft's web-based communication tools - including Hotmail and instant messaging accounts - has been intermittently blocked across the globe since about midday GMT on Tuesday.

The company previously said that it had resolved the problem and that access to Hotmail had been restored, but today Times Online has continued to receive comments from users in Europe and North America saying that their accounts were frozen.

In a statement this afternoon, Microsoft said: "We are aware that some customers may be experiencing difficulty accessing their Windows Live accounts. We’re actively investigating the cause and are working to take the appropriate steps to remedy the situation as rapidly as possible."

Many of the more than 80 million people who use Hotmail worldwide have expressed frustration that Microsoft claimed to have fixed the problem when in fact it was still working to resolve it.

"I think I'm most irritated about the fact that Microsoft is downplaying the extent of the problem," wrote one Hotmail user yesterday. "The outage is not resolved, and is now going into its second day."

The company has not given any indication as to the cause of the outage.

Several others have also suggested they will shifting to rival mail services such as Yahoo! or Gmail, Google's offering, as a result of the outage.

"I've just swapped from Hotmail to Gmail yesterday," wrote Martyn, from Dubai. "Not being able to access my account yesterday was the final straw. I've found Hotmail increasingly unreliable and I get lots of spam too."

'JCP', from La Jolla, in California, wrote: "For me, this is the last straw. It's hard to migrate to another service like gmail or yahoo, but the unreliability of hotmail has just gotten to be too consistent."

Among the countries where users have reported difficulties using Hotmail were the US, the UK, Finland, the Netherlands, France, the Czech Republic, and Honduras.

"Getting the login page, but won't go any further," wrote Nancy, a Hotmail user from Luton, just after noon today.

"I'm still down. Thursday 28th February at 06.34 in the morning. What is going on?," wrote Pat from Harrogate.

Hotmail, which has been rebranded Windows Live Hotmail since being taken over by Microsoft, accounts for 24 per cent of the world's web-based e-mail accounts, a fraction behind Yahoo!, which has 25 per cent. More than ten million people use the service in the UK alone, according to Nielsen Online.

Two weeks ago, eight million BlackBerry customers in the US were left without access to their e-mail for several hours. It was the second time in a year that the network had failed.

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