Lawyers for the nine US states suing Microsoft have accused the firm of arrogance during the closing arguments of the anti-trust case.

"Somehow they know better than anybody else what is good for the PC ecosystem," said lawyer Steven Kuney.

At the request of the US District Judge Colleen Kollar-Ketelly, Mr Kuney also prioritised the demands of the states.

Lawyers representing Microsoft denied that the company sought a monopoly position, and refused to offer any possible concessions.

Tougher penalties

Mr Kuney urged the judge to approve penalties put forward by the nine states, which are tougher than those agreed between Microsoft and the federal government last year.

He said the most important proposal was to force Microsoft to make more technical information available to allow software developers to create products that work with the Windows operating system.

"If you forced us to articulate the single highest priority - that's it," Mr Kuney said.

He added that computer makers should also have more flexibility and protection from restrictive contracts and retaliation by Microsoft.

He said the measures in total would force Microsoft to "behave more like a company facing competition and less like a firm existing in a comfortable monopoly."

Microsoft hits back

But Microsoft attorney John Warden said the states' lawyers had misrepresented the firm's position.

"Microsoft does not claim that monopoly is the preferred form of industrial organization," he said.

"We haven't claimed that we're immune from the law or anything of that kind."

He said the measures that the states were seeking were too tough.

"The remedies sought by the states would destroy the balance struck by the executive branch," he said, referring to last year's settlement with the US Justice Department.

And he said Microsoft would not put forward any concessions to the states.

"This proposed decree is fundamentally flawed," Mr Warden said.

"We can't remedy any of this by changing a few words here and there."

Long running battle

In 2000, Microsoft was ordered to be split up after being found guilty of exploiting its dominant position in the computer operating system market.

But the trial findings were overturned on appeal, and Microsoft then agreed a less radical solution with nine states and the US Justice Department.

The nine remaining states want to see Microsoft subject to more radical penalties, including being forced to make Windows easier to customise.

They say the move would allow computer makers more freedom to feature rival software on PCs, allowing greater consumer choice.

But Microsoft has said that the firm would be crippled if such conditions were imposed.