Fighting erupted in Idlib late last month, effectively shattering a cease-fire negotiated by Russia and Turkey that had been in place since September. Russia has firmly backed President Bashar Assad's government in the eight-year civil war, while Turkey has supported the opposition.
The pro-government Syrian Central Military Media said government forces responded to shelling by militants Sunday on the edge of Idlib. It gave no further details.
The Britain-based Syrian Observatory for Human Rights, an opposition war monitoring group, reported an airstrike on the town of Khan Sheikhoun, saying it inflicted casualties.
The opposition's Syrian Civil Defense also reported shelling near the town of Jisr al-Shughour without reporting any casualties.
Syrian government forces intensified their attacks as of April 30 on Idlib. The area is home to some 3 million people, many of whom are internally displaced. The last round of violence also displaced some 180,000 in rebel-held areas.