U.N. investigates seven Syrian chemical cases, some after August 21 attack BEIRUT (Reuters) - U.N. chemical weapons inspectors in Syria are investigating seven cases of alleged chemical or biological weapons use, including three incidents around Damascus after the August 21 attack which almost triggered U.S. air strikes. The inspectors expect to finalize their work in Syria on Monday and issue a report by late October that will give more details of the August 21 incident which they have already said involved the use of sarin gas, a statement from the United Nations in Damascus said on Friday. The United States and its Western allies said the initial report showed Damascus was behind the attack, which killed hundreds of people. President Bashar al-Assad's government has denied the accusation, blaming rebels instead. The incidents also include an alleged chemical weapons attack in March in the northern town of Khan al-Assal, where authorities say rebels killed 25 people, including 16 soldiers. Rebels said government forces were behind it. The two other cases from earlier this year both date back to April - one in the Aleppo district of Sheikh Maqsoud and another in the town of Saraqeb in the northern province of Idlib. The three most recent incidents were in Bahhariyeh and Jobar, both east of central Damascus, on August 22 and 24, and Ashrafiat Sahnaya to the southwest of the capital on August 25, the U.N. statement said. The team returned to Damascus on Wednesday to resume its work and "expects to finalize its activities in the country by Monday," the statement said. Reporting by Dominic Evans; Editing by Alison Williams and Robin Pomeroy