"NOT ENOUGH"
The UN refugee agency, the UNHCR, said the EU decision was an "important first step in a united European response to managing the refugee crisis".
Spokesman Melissa Fleming added: "This must be coupled with the immediate creation or expansion of facilities in Greece and Italy to receive and assist large numbers of arriving refugees and migrants, and where people would be screened and identified for relocation."
The 120,000 people the bloc was seeking to share out were equivalent to just 20 days' worth of arrivals at the current rate, Fleming said earlier.
Together with 40,000 covered in an earlier agreement, the European Commission said the EU was now in a position to relocate a total of 160,000 people "in clear need of international protection" in the next two years.
Refugees and migrants arriving in Greece and Italy have been streaming north across the continent to reach more affluent nations such as Germany, triggering disputes between governments in central and eastern Europe as they alternately try to block the flow or shunt the burden on to their neighbours.
Norway became the latest member of Europe's 26-nation Schengen area, where people can normally travel across frontiers without showing a passport, to say it would intensify border controls.
The Organisation for Economic Co-operation and Development said Europe could expect a record one million people to request asylum this year, and almost half would probably qualify to be taken in.
In Germany, by far the most popular destination, the head of domestic intelligence said there was a big worry that radical Islamists living in the country could try to recruit young refugees "who could be easy prey".
EU leaders will hold an emergency summit on Wednesday at which they want to focus on ramping up aid for Syrian refugees in Turkey and the rest of the Middle East and tightening control of the bloc's external frontiers.