Lord Robertson (right) sees some signs of improvement

He said 150 rebels had been arrested and several tonnes of military equipment seized by Nato-led peacekeepers in recent days.

Correspondents say some Western diplomats concede that the Macedonian constitution may eventually have to be changed to satisfy Albanian demands.

'Renewed dialogue'

Lord Robertson, who was accompanied by the ambassadors of all 19 Nato members, said he had seen some signs of improvement since his last visit.

"It's the second time I've been here in these last eight days and I see progress already made," he said.

"There is renewed and intensified dialogue now going on with the political parties here."

Not everyone appreciates Nato's involvement in Macedonia

Lord Robertson's visit follows all-party talks on Monday aimed at addressing Albanian grievances.

And it coincides with what the army describes as the longest period of calm since the conflict with ethnic Albanian rebels began six weeks ago.

The Macedonian authorities say they have successfully pushed the rebels across the border into Kosovo, but guerrilla commanders maintain they have simply fallen back to regroup.

On Tuesday the Macedonian Government reopened the border with Kosovo in an effort to return the area to normal.

Demands

Monday's talks were attended by the largest ethnic Albanian party, the Democratic Party of Albanians (DPA), which is in the governing coalition.

But they were boycotted by the main ethnic Albanian opposition party, the Party for Democratic Prosperity.

The leader of the DPA, Arben Xhaferi, has threatened to pull out of the government unless its demands are met within a month.

He has also warned that the rebels will return if progress is not made.

Correspondents say the brief rebellion has changed the political situation in Macedonia.

The government now accepts that the grievances of the Albanian minority have to be addressed, and the hand of Albanian politicians strengthened.