Thousands of Syrians fleeing civil war or planning to stock up on supplies crossed into northern Iraq at the weekend after Iraqi Kurdish authorities reopened a long-closed border.

Thousands of Syrians fleeing civil war or planning to stock up on supplies crossed into northern Iraq at the weekend after Iraqi Kurdish authorities reopened a long-closed border, the UN refugee agency said Tuesday.

On Sunday afternoon, authorities reopened the Peshkhabour border at the Tigris River, which had been closed since mid-September, allowing 2,519 Syrians to cross into the country by barge, UNHCR spokeswoman Melissa Fleming told reporters in Geneva.

The border crossing is currently the only one open between Syria and Iraq, she said.

Iraqi authorities decided to close the border in September after facing an exodus of some 60,000 Syrians, UNHCR said.

Authorities in Iraq's Kurdistan region had told the UN agency they had now decided to allow Syrians claiming they did not want to stay in the country to visit for up to seven days, allowing them to stock up on supplies before returning.

Those wishing to stay meanwhile needed to register their request for refugee status with authorities.

Around 400 of the newcomers had gone to UNHCR to ask for assistance as refugees, and were taken to the Gawilan refugee camp, which counts some 3,000 residents and lies between Erbil and Dohuk.

UNHCR staff had on Monday seen 350 of the new arrivals load barges and go back to Syria with generators, kerosene heaters and other supplies, she said.

Some 210,000 Syrians have been registered as refugees in Iraq since the conflict in their country began in March 2011.

In total, more than 2.35 million people have fled across Syria's borders, while millions more have been displaced inside the country during the nearly three-year conflict.