UN Secretary-General Antonio Guterres on Sunday urged Iraqi Kurds to scrap plans to hold a referendum on independence later this month, arguing it would detract from the fight against Islamic State jihadists.

Guterres said in a statement that any dispute between the Iraqi government and the Kurdistan regional government should be resolved through dialogue and "constructive compromise."

The leaders of Iraq's autonomous Kurdish region are set to hold a referendum on independence on September 25.

Guterres said "any unilateral decision to hold a referendum at this time would detract from the need to defeat ISIL", the Islamic State group.

It would also undermine reconstruction efforts and the return of refugees, he added.

On Friday, the United States said the referendum should be called off, a stance also pushed by neighboring Turkey which fears another source of conflict in the region.

Iran warned on Sunday that independence for Iraqi Kurdistan would mean an end to all border and security arrangements with the regional government.

Guterres urged Iraqi leaders to "approach this matter with patience and restraint" and offered UN help to address the issue.

UN envoy to Iraq Jan Kubis told Iraqi Kurdish leader Massud Barzani last week that the United Nations was ready to broker negotiations to address "all the problems and outstanding issues" between the Kurds and Baghdad, according to a document obtained by AFP.

The negotiations would aim to reach a deal within two or three years on the "principles and arrangements" for future relations between Baghdad and the Kurdish region, the document said.

In return, Barzani's administration would agree to postpone the referendum at least until the end of negotiations.