PARIS (Reuters) - France said on Thursday it was paying close attention to evidence from a U.N. investigation that shows Syrian forces used chemical weapons in different attacks in 2017 and before. French President Emmanuel Macron said in May, barely two weeks after his inauguration, that the use of chemical weapons in Syria would represent a red line and result in reprisals.     U.N. war crimes investigators said on Wednesday that Syrian forces have used chemical weapons more than two dozen times during the country s six-year civil war, including a deadly attack that led to U.S. air strikes on government planes. Syrian government forces carried out chemical attacks seven times between March 1 and July 7, according to the U.N. investigation, suggesting attacks would have taken place after Macron s warnings.   We are paying extremely close attention to the consistent evidence revealed by the commission regarding different types of chemical attacks on 2017,  a foreign ministry spokeswoman said in response to a question on what Paris would do if its red line had been crossed.   She said the foreign ministry called for those behind the April 4 sarin attack on Khan Sheikhoun in Idlib province, which killed more than 80 civilians, to be held to account. 