Ban has asked the U.N. High Representative for Disarmament Affairs, Angela Kane, to travel to Damascus to push for access for the U.N. team, which arrived in Syria on Sunday to investigate several previous claims of chemical weapons use.
Syrian President Bashar Assad's government is under increasing pressure from Western and Gulf Arab countries and Assad's ally Russia to allow access to the rebel-held site of Wednesday's pre-dawn attack. The opposition Syrian National Coalition has also urged U.N. access.
"The Secretary-General believes that the incidents reported yesterday need to be investigated without delay," Ban's press office said in a statement. "A formal request is being sent by the United Nations to the government of Syria in this regard. He expects to receive a positive response without delay."
Speaking in Seoul on Friday, Ban said he was pressing hard for full cooperation of the Syrian government so that the mission can swiftly initiate the investigation.
Syria's government offered no immediate public response to calls on Thursday for the U.N. team to inspect the site.
Assad opponents gave death tolls from the attack ranging from 500 to well over 1,000 and said on Thursday that more bodies were still being found. The Syrian government has repeatedly denied using chemical weapons.
The U.N. team, led by Swedish scientist Ake Sellstrom, is already looking into three claims of chemical use in Syria's conflict. The United Nations has received a total of 14 reports of possible chemical attacks - one from Syria's government and the rest from Britain, France and the United States.
Inquiry won't place blame
The Syrian government and the opposition have accused each other of using chemical weapons, and both have denied doing so. The U.N. inquiry will try to establish only whether chemical weapons were used, not who used them.
Ban said on Monday that if the experts found that chemical weapons had been used then it would be up to "the international community to determine what course of action should be taken to prove ... accountability and what needs to be done."
"Use of chemical weapons is a violation of international law and international human rights law," Ban told a news conference.
The United Nations has been demanding unfettered access in Syria to conduct the investigation. Sellstrom's team consists of experts from the Organization for the Prohibition of Chemical Weapons and the World Health Organization.
Ban appointed Sellstrom to lead the inquiry in March, but diplomatic wrangling and concerns over safety prevented his team from entering Syria until this week.
Syria is one of seven countries that have not joined the 1997 convention banning chemical weapons. Western countries believe it has stockpiles of undeclared mustard gas, sarin and VX nerve agents.
The United Nations says more than 100,000 people have been killed in the Syrian conflict since 2011.
More than 1.9 million Syrians have fled the country - two-thirds of those since the start of the year - and more than 4.2 million people have been internally displaced, the United Nations has said. Most of those in need are women and children.
First published August 22 2013, 7:13 PM