The invention relates to antibacterial compounds of formula (I) wherein R1 is H or halogen R2 is alkynyloxy or the group M R3 is H or halogen M is one of the groups (A, B, C, D) wherein A is a bond, CH2 CH2, CH=CH or C=C and R1A, R2A, R3A, R1B and R1C are as defined in claim 1 and salts thereof.