Vessel sailing under British flag have been banned from docking in Buenos Aires, after the provincial legislature decided to stop them "mooring, loading or even carrying out logistical actions".
The main aim of the bill is thwarting British oil and gas research near the disputed Falkland Islands, was brought forward by Patricia Cubria, that is a member belonging to President Cristina Kirchner's Front for Victory coalition.
"It is an instrument which continues our struggle for the sovereignty and natural resources of the Malvinas [Falklands]," Ms Cubría stated.
The Argentine government started legitimate action in June against 5 British exploration firms that had been operating near the Falklands.
The vessel ban follows last year's shutdown of ports by the trading bloc Mercosur (Brazil, Argentina, Paraguay and Uruguay) to vessels flying the Falklands flag.
Buenos Aires province is the nation's largest and home to 40% of its citizens as well as having its main ports, however the Port Montevideo in Uruguay is 200 km far away across the wide mouth of River Plate.
Last year, 2 Norwegian vessels, thought to be British, sailed to the Falklands in search of oil, docked at La Plata, near to Buenos Aires, sparking mass protests.
In December, countries that belong to South American trading bloc Mercosur closed its ports to vessels floating the Falklands flag.
Two P&O cruise liners were also banned from docking in Argentina in February after they visited the islands.