The European Union has slapped sanctions on four high-ranking military officials of the Assad regime over the use of chemical weapons in war-torn Syria.

EU headquarters said in a statement Monday that the move is "in line with the EU's policy to fight the proliferation and use of chemical weapons."

The decision brings to 239 the number of Syrian individuals hit with travel bans or asset freezes over the violent suppression of civilians since a civil war erupted in 2011.

The four were not named but will be identified in the EU's official journal on Tuesday.

Another 67 entities are affected by asset freezes while the EU also has in place other sanctions against Syria as a whole, including arms and oil embargoes plus investment restrictions and a freeze of Syrian central bank assets.

These measures were last extended in May last year until June this year.

"The EU remains committed to finding a lasting political solution to the conflict in Syria under the existing UN-agreed framework," the statement said.