Syria's U.N. envoy says his government is not seeking any escalation of violence with Turkey and is investigating the source of the cross-border shelling that killed five Turkish civilians.

Ambassador Bashar Ja'afari read reporters a letter he delivered today to the U.N. Security Council which sent Syria's "deepest condolences" to the families of the victims and to Turkey.

But he said it did not include an apology because the investigation of the incident has not been completed.

Ja'afari said that the return shelling from Turkey this morning injured two Syrian army officials.

The ambassador said his government was calling on Turkey to act "wisely, rationally" and prevent infiltration of "terrorists and insurgents" and the smuggling of arms across the border.