"Steps such as demands for independence that can cause new crises and conflicts in the region must be avoided. We hereby call on the Iraqi Kurdish Regional Government to abort the initiative they have launched in that direction," Erdogan said in a speech to the UN General Assembly.

"Ignoring the clear and determined stance of Turkey on this matter may lead to a process that shall deprive the Iraqi Kurdish Regional Government of even the opportunities it currently enjoys," he said.

Turkey, which has already warned against the vote, has its own long-running conflict with separatists among its sizable Kurdish minority and has also vowed to quash any Kurdish state from emerging in war-torn Syria.

In a likely unstated warning, Turkey on Monday launched a military drill with 100 vehicles including tanks on the Iraqi border.

Iraqi Kurds will vote on Sunday in the non-binding referendum on whether to declare independence in a region that has already been autonomous since the aftermath of the 1991 Gulf War.

Virtually all countries including the United States and Iran oppose the referendum -- with the exception of Israel, which sees a possible opening in a hostile region.