DAMASCUS (AFP) -- U.N. envoy Staffan de Mistura paid a surprise visit Sunday to a church near war-wracked Syria's capital in a show of solidarity with the country's Christian minority targeted by jihadis. An AFP photographer said de Mistura traveled in a two-car U.N. convoy to a Greek Catholic church in Jaramana, southeast of Damascus, and met with priest Toma Asitivo Kaka. The church has been used as a place of refuge for Assyrian Christians fleeing the chaos of Iraq after the 2003 U.S.-led invasion of that country. His visit coincided with a mass of solidarity with the scores of Syrian Assyrians kidnapped by ISIS jihadis in Hassakeh province of northeast Syria. Last week, ISIS kidnapped 220 Assyrians in the Tal Tamr area where the extremist Islamist group has seized control of 10 Christian villages, according to the Syrian Observatory for Human Rights activist group. Almost 5,000 people have since fled to Kurdish- and government-controlled areas. The monitoring group reported that an ISIS "court" has ordered the release of 28 of the abducted Assyrians. De Mistura, who left for Lebanon after visiting the church, held talks Saturday in the Syrian capital to try to finalize a deal to freeze fighting in the war-ravaged second city of Aleppo. He met Foreign Minister Walid Muallem and agreed to send a delegation from his Damascus office to Aleppo on a fact-finding mission, state news agency SANA said, without giving a date. The Swedish-Italian diplomat "hopes to set in motion as soon as possible his project" to halt fighting in Aleppo for six weeks, said a member of his delegation. He has met government officials and opposition chiefs in recent weeks to promote his plan for a temporary truce in Aleppo in order to move aid into the northern city. Once Syria's commercial hub, Aleppo has been devastated by fighting that began in mid-2012, and the city is now split between loyalist forces and rebels. About 220,000 people have been killed in Syria since its conflict began in March 2011 with anti-government protests that spiralled into a multi-sided civil war drawing foreign jihadis.