SIDON, Lebanon (AP) _ A British official from a private relief organization and his Syrian aide disappeared in Lebanon, and one official of their group said Friday that they had been kidnapped.

The purported abduction came near the end of a week that saw two Scandinavian employees of the United Nations and a West German engineer released in Lebanon.

Peter Coleridge, the 44-year-old Middle East coordinator of Oxfam, and Oxfam's Lebanon representative Omar Traboulsi, 31, a Syrian, were kidnapped Thursday evening, spokesman John Magrath said in Oxford, England.

Coleridge was on his first trip to Lebanon in three years.

''We've had conflicting reports as to whether they are still being held or not,'' Magrath said. But Nissrine Rawda, an official at Oxfam's Beirut office, said there were ''no eyewitnesses confirming the abduction.''

Sunni Moslem leftist leader Mustafa Saad, whose Nasserite militia controls Sidon, told reporters the two Oxfam officials have been ''detained for questioning'' by an unidentified Palestinian group in Sidon's Ein el-Hilweh refugee camp.

''I expect their release within hours, God willing,'' Saad said. ''This is not an abduction. There is a security mishap in the camp.''

He said Coleridge had visited the Hittin area south of Ein el-Hilweh in 1982, when it was devastated by Israel's invading army.

''When he returned this time he took pictures of the area's reconstruction and a group inside the camp seized him for questioning, fearing he might be taking espionage photographs,'' Saad added.

Saad declined to name the group which he says is holding Coleridge and Traboulsi.

''But I have stressed upon the party holding him that he should be released in time to catch his scheduled flight to London on Saturday,'' Saad told The Associated Press.

He said Coleridge was booked on Middle East Airlines Flight 201 to London at 11:30 a.m. Saturday.

Police in Sidon, an ancient city 25 miles south of Beirut, confirmed the two men had been missing since the night before, but could not say for sure how they vanished.

''They may have been seized by gunmen of the Moslem Ulema grouping,'' said a Sidon police spokesman who could not be identified in keeping with regulations. ''We are acting on this assumption in our investigation.''

The Moslem Ulema is a fundamentalist Sunni Moslem faction headed by Sheik Maher Hammoud and is influenced by the pro-Iranian Hezbollah, or Party of God.

Hammoud, however, disclaimed any involvement in the abduction.

''Why should I be blamed for every foreigner who is abducted in Sidon?'' Hammoud told The Associated Press.

Hezbollah is believed to be the patron of underground factions holding many of 22 other foreigners held hostage in Lebanon.

Two U.N. Scandinavian relief workers - Jan Stening, 44, of Sweden, and William Jorgensen, 58, of Norway - were freed unharmed Tuesday after 25 days of captivity.

The U.N. Relief and Works Agency, with which the two Scandinavians served, had blamed their abduction on Palestinians acting without a political motive.

Coleridge and Traboulsi traveled to Sidon from Beirut on Thursday morning on a routine visit to inspect relief groups supported by Oxfam, a British charity that aids refugees and poor people in many countries.

Police said the missing pair had lunch Thursday in Sidon's Skandarani district with Alia Shammaa, who heads the Ghassan Kanafani Foundation, a Palestinian charity that receives aid from Oxfam.

They left Mrs. Shammaa's house at 3:30 p.m. and went to the suburban Ein el-Hilweh refugee camp in an orange station wagon, the police spokesman said.

They left Ein el-Hilweh to Sidon at 4:15 p.m., the spokesman said.

The vehicle was last seen at Jerusalem Square, about a half a mile from Mrs. Shammaa's house, the spokesman said.

Jerusalem Square is about 100 yards from Sheik Hammoud's residence in Sidon, Lebanon's third largest city.

Coleridge joined Oxfam in June 1981 and lives in Oxford with his wife, two daughters and son. Traboulsi is not married.

British Ambassador John Gray visited Mrs. Rawda at mid-afternoon and said afterwards: ''I have no confirmation of the (abduction) story one way or the other.''

The embassy's military attache Col. Patrick Hyland earlier said the reported abduction was ''a false alarm at the moment.''

The reported abduction came a day after pro-Iranian Shiite Moslem kidnappers released West German industrial engineer Ralph Schray, 30, from 35 days of captivity in west Beirut.

The 22 foreigners missing and believed kidnapped in Lebanon since 1985 include nine Americans, four Frenchmen, three Britons, a West German, an Irishman, an Italian, an Indian and two unidentified men.

Longest held is American Terry Anderson, chief Middle East correspondent for The Associated Press. He was kidnapped March 16, 1985.