On his third visit to the troubled Balkan country in as many months, Robertson met with leaders of majority Macedonians and ethnic Albanians who in August signed the peace pact on ending an ethnic Albanian insurgency but have not carried out all its provisions.
"There are sizable, real risks of a return to violence ... implementation of the peace agreement is six weeks overdue" from a late September deadline, Robertson warned.
He met with President Boris Trajkovski, government and party officials representing the rival communities.
"Our priority today is the amnesty and to get its technical details worked out ... and to see a completion of the parliamentary process,'' Robertson said, referring to an envisaged change of Macedonia's constitution granting broader rights to ethnic Albanians, nearly a third of Macedonia's 2 million people.
Ethnic Albanian rebels took up arms in February, saying they were fighting for broader rights. After dozens died in clashes with government forces, Macedonians agreed to sign the accord despite claiming that the insurgents wanted to secede a northwestern, ethnic Albanian-populated region.
"There is responsibility on all parties to deliver on what has been promised ... if there is going to be a lasting peace in this country," Robertson said.
The parliamentary procedure to adopt 15 constitutional amendments on minority rights has stalled over a preamble that defines what communities live in Macedonia. A key ethnic Albanian political party contends that a draft proposal still suggests a dominance by Macedonians.
The amnesty would include the insurgents who recently handed over nearly 4,000 weapons. So far, Macedonian President Boris Trajkovski has made only a general pledge to pardon the ex-fighters, except those who may have committed war crimes.
The Interior Ministry, a hotbed of anti-treaty sentiment, is prosecuting 224 ex-rebels and dozens are believed to be in jail on murky charges of "terrorism" or weapons possession.
Former guerrilla commander Ali Ahmeti and 10 top associates face domestic "war crimes" charges which they have denied and for which Western diplomats believe there is no hard evidence.
Western officials insist that only the Netherlands-based U.N. war crimes tribunal for former Yugoslavia is allowed to prosecute and punish such violations of international norms.
"We discussed that the question of amnesty be resolved through a special law" in the country's parliament, said Justice Minister Ixhet Mehmeti, who is ethnic Albanian, after meeting with Robertson.
"But there are no conditions yet for that" due to enduring tensions, Mehmeti said, adding that "other legal instruments" were considered, including a legally binding presidential pardon to guarantee freedom of prsecution to the ex-guerrillas.
Many of the ex-insurgents are stewing in dead-end, half-destroyed highland villages or across the border in Kosovo, unable to resume jobs or an education in the cities for fear of arrest at police checkpoints on the way.
Although rebels handed thousands of weapons in to NATO under the peace agreement, gunfire still clatters near truce lines after dark, though Western monitors say it has been aimed at no one so far.
© MMI, CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press and Reuters Limited contributed to this report