BRUSSELS — International donors pledged $15.2 billion on Wednesday to help keep Afghanistan’s beleaguered government afloat for the next four years, despite growing reluctance to pour more money into a corruption-plagued country wracked by conflict.

The promised funds, from more than 70 nations, fell short of commitments made in Tokyo in 2012, but the European Union’s development commissioner, Neven Mimica, said the pledges ‘‘surpassed some of our best-case scenarios.’’

As the donors met, Afghan forces, backed by US helicopters, battled the Taliban in the northern city of Kunduz for the third straight day, following an attack launched by insurgents earlier this week.

The Afghan government is estimated to be capable of meeting only 20 percent of its budget, and about 39 percent of the Afghan population lives on less than $1.35 a day.

But Afghanistan has survived with Western aid and military support for 15 years, since a US-led coalition in 2001 ousted the Taliban for harboring Osama bin Laden.

The European Union and its 28 member states on Wednesday pledged $5.6 billion in total until 2017, making it the biggest donor.

‘‘It is truly a remarkable day,’’ Afghan President Ashraf Ghani told reporters.

But he acknowledged that no money would be forthcoming if the government does not crack down on corruption and crime and take the upper hand against the insurgents.