U.N. says Afghan situation 'very serious'

TEHRAN, Iran (CNN) -- A top U.N. official warned Tuesday of a rapidly worsening humanitarian situation in Afghanistan.

"I believe the situation is getting very, very serious. Winter is coming very soon, and the international humanitarian community needs to act very quickly," said Kenzo Oshima, undersecretary-general and emergency relief coordinator.

Oshima spoke with reporters Tuesday evening in the northeastern Iranian city of Mashhad, 190 miles (300 kilometers) from the Afghan border, where the first U.N. relief flight to Iran is to arrive on Wednesday.

A DC-8 is due with 40 tons of tents, part of a donation of 1,200 tents provided by Britain.

A second flight will arrive in the coming days with the remaining tents, 350 rolls of plastic sheeting and cotton tarpaulins to assist up to 400,000 people.

On Wednesday and Thursday, Oshima will be in Tehran where he will deliver a message from U.N. Secretary-General Kofi Annan to Iranian President Mohammad Khatami. The United Nations has urged the Iranian government to open its borders to Afghan refugees fleeing a possible U.S.-led military attack in Afghanistan.

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Iran sealed its 580-mile (940-kilometer) border with Afghanistan 10 days ago to prevent a new flood of refugees, saying it will instead help facilitate relief inside the Afghanistan border.

Iran and Pakistan are each already home to at least 2 million Afghan refugees, according to the U.N. High Commissioner for Refugees.

The U.N relief agency has warned of a "worst case scenario" in which up to an additional 1.5 million Afghans may flee to neighboring countries.

Meanwhile, a second UNHCR emergency airlift flight arrived Tuesday in Peshawar, Pakistan, carrying 17,000 blankets and 250 rolls of plastic sheeting.

More UNHCR staffers have arrived in Pakistan and are being sent to Islamabad, Quetta and Peshawar to support the emergency operation that will provide aid to Afghan refugees.

The first team of specialists was sent to the Khyber agency in northwest Pakistan to begin work on a new refugee camp that could accommodate up to 10,000 Afghan refugees if there is a major influx.

Last week, four U.N. teams and Pakistani government staffers went to six tribal areas to inspect 75 sites for refugees along the Afghan border. They found that 23 were "suitable" to use.

Four of the sites will be established in the Khyber agency, Kurram, North Waziristan and Bajaur -- tribal areas along the Afghan border.

-- CNN's Kasra Naji contributed to this report.