Croatia's energy group INA said it had withdrawn most of its employees from its production fields in Syria, but output remains largely unaffected.
"Safety of our employees is our absolute priority. We follow developments in Syria closely and we decided at the end of January to withdraw most of our employees as security conditions have worsened recently," INA said in a statement.
It also said that the gas production, now mostly run by local staff, was continuing without major difficulties.
"There have been no attacks on our personnel in Syria. We faced minor incidents like a theft of one of our vehicles," INA said.
Syria is in upheaval amid bloody protests against the rule of President Bashar al-Assad.
In the last quarter of 2011 INA reduced production on its oil and gas fields in Syria by 2,800 barrels of oil per day following the European Union sanctions on the Middle East country.
In December it said developments in Syria could negatively affect its business and profitability.
INA has not disclosed its total output in Syria but said the overall output from all of its oilfields worldwide amounts to 76,223 barrels per day.