Buenos Aires approved a law early Friday authorizing unrestricted abortions in cases of rape or when the mother's life is in danger.
The city's legislature passed the measure by a close 30-29 vote with allies of President Cristina Kirchner edging out a bloc led by Buenos Aires Mayor Mauricio Macri, a potential rival for the presidency in 2015.
The bill prohibits "medical, bureaucratic or judicial obstacles" to abortions in cases of rape or where there is a high risk to the health of the mother.
Attempts by Argentina's Congress to pass a federal law decriminalizing abortion have failed, however, opposed both by Kirchner and the Catholic Church.
In neighboring Uruguay, the lower house of the Congress voted this week to legalize abortions in the first trimester, with the requirement that women first consult a medical team on the risks associated with the procedure and options to terminating a pregnancy.
The Uruguayan Senate was expected to approve the bill later this year, which would make it only the second Latin American country, after Cuba, to legalize abortion.