Warplanes launched heavy attacks on the two last major rebel-held areas in Syria, killing at least 29 people in the Ghouta suburb near the capital and choking people with gas in Idlib in the northwest, rescue workers and a war monitor said Monday.

The Syrian government has consistently denied using chlorine or other chemical weapons during Syria's conflict.

Rescue workers and medical groups have accused government forces of using chlorine gas against the rebel-held Eastern Ghouta at least three times over the last month, most recently Thursday.

The German government called for a thorough investigation into reports Syria had used chemical weapons in both Idlib and Eastern Ghouta.

The Observatory said the new Turkish observation post was near the village of Al-Eis. That would place it less than 5 kilometers from territory held by Syrian government forces and their allies, and deeper inside Syria than the three observation posts set up by the Turkish army so far.

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