Wednesday’s meeting focused on rebuilding security structures, personnel training, border controls, drug trafficking and terrorism.
"Participating countries at the conference in Qatar for rebuilding the police force in Afghanistan have agreed to donate $340 million," the official told AFP, requesting anonymity.
Organisers said on Tuesday that Afghanistan required at least $200 million to support the development of a police force.
Afghan Interior Minister Ali Ahmad Jalali urged participants - who included representatives from Britain, France, Japan, Turkey, the United Arab Emirates, the United States and the European Union - to keep giving money as "an investment for security in the region".
"We have neither the equipment nor the capacity to face up to organised crime and terrorism," Jalali said at the opening of the two-day meeting.
The policing powers of the Afghan government have been largely limited to the capital Kabul, with the rest of the country either under the control of regional commanders or effectively lawless.
War-torn Afghanistan launched a disarmament campaign on Monday to demobilise tens of thousands of irregular troops loyal to powerful commanders before the first post-Taliban elections in September.