Ban will meet in New York on Monday with the two envoys who struck the accord, spokeswoman Morana Song said.
The UN and Syrian government said in a joint statement issued late Friday that an accord had been reached "on the way forward" in the investigation, following the visit to Damascus by Ake Sellstrom, head of the UN inspectors, and Angela Kane, the UN disarmament envoy.
The statement did not say whether UN inspectors would be allowed into Syria as Ban has demanded.
"Ms Kane and Dr Sellstrom are expected to report to the secretary general on Monday on the result of their visit to Syria," Song said.
"We will have no further comment until the secretary general has had an opportunity to get briefed on the visit and review the situation," she added.
Kane and Sellstrom were in Damascus on Wednesday and Thursday. They met with Foreign Minister Walid al-Muallem and deputy prime minister Qadri Jamil, said the joint statement.
"The discussions were thorough and productive and led to an agreement on the way forward," the joint statement added, without giving any other detail.
The UN says it has been given reports of 13 chemical weapons attacks during the 28-month old conflict.
Ban has demanded widespread access to investigate all allegations. Syria has insisted the UN only investigate its claim that opposition rebels used chemical weapons in the town of Khan al-Assal on March 19.
Britain, France and the United States say all the attacks were carried out by President Bashar al-Assad's forces.
Russia, Assad's main ally, says its inquiry found opposition rebels used sarin gas in Khan al-Assal.
The United Nations said Friday it reached an agreement with Syria on an inquiry into the use of chemical weapons, but did not say UN inspectors would be allowed in.
Two UN envoys went to Damascus on Tuesday and Wednesday and held talks with Syria's deputy prime minister and foreign minister, read a brief UN statement.
Syrian opposition groups are ready to attend a new Geneva conference to find an end to the conflict provided the government is committed to relinquish power to a transitional body, diplomats said Friday.
Leaders of the Syrian National Coalition made a strong commitment to fight extremism and terrorism, British UN Ambassador Mark Lyall Grant told reporters following a 3-hour meeting. His remarks were backed by French Ambassador Gerard Araud.
"We received a very positive message from Ahmad al-Jarba, who gave a clear commitment to the Geneva conference and the communique calling for a transitional body," Grant said.
Russian Ambassador Vitaly Churkin called the meeting "useful."
He added: "We should not be carried away (by the commitment). The meeting was not to officially recognize the coalition."
Moscow has applauded the Syrian authorities' readiness to cooperate with visiting United Nations experts to establish all of the instances of chemical weapons use in the country.
"We applaud the Syrian government's constructive approach toward cooperating with UN High Representative for Disarmament Affairs Angela Kane and the head of the UN experts who are currently in Damascus to verify [Swedish chemical weapons expert Ake] Sellstrom's claims regarding the use of chemical weapons in Syria," the Russian Foreign Ministry said on its website following a meeting of Deputy Foreign Minister Mikhail Bogdanov and Syrian Ambassador to Moscow Riyad Haddad.
Voice of Russia, AFP, Interfax