The United Nations says it aims to resettle more than 450,000 Syrian refugees, about one-tenth of those now in neighbouring countries, by the end of 2018.
The UN refugee agency is urging countries worldwide to take in Syrians for resettlement as well as for humanitarian reasons of family reunification, medical treatment or scholarships to complete their studies.
More than 4.8 million Syrian refugees have fled to Turkey, Lebanon, Jordan and Egypt to escape a war that has killed more than 250,000 people since 2011 and left 13.5 million inside Syria in need of aid.
An additional half a million people are estimated to have fled to Europe, especially Germany, since early 2015.
Syria's pre-war population was around 22 million.
A ministerial-level conference on Wednesday will "focus on the need for generating a substantial increase in resettlement and other answers for their plight", spokesman Adrian Edwards of the UN High Commissioner for Refugees (UNHCR) told a briefing.
"We estimate that 10 percent of Syria's 4.8 million refugees fall into the highly vulnerable category.
"That means that well over 450,000 places will be needed before the end of 2018."
The UNHCR is hoping for a "separate commitment" from the European Union than relocation offered under a controversial agreement reached with Turkey this month, Edwards told Reuters.
Under that deal, for every Syrian returned from the EU to Turkey, another would be resettled from Turkey within the bloc.
Since 2013, mainly Western countries have offered some 179,150 resettlement places to Syrian refugees, UNHCR figures show.
These include 25,000 resettled in Canada in recent months, while nearly 42,000 have benefited from Germany's large programs of humanitarian admissions and private sponsorship.
UNHCR says it asked the uses last month to consider 32,369 Syrian refugees for resettlement.
"Small countries like Portugal are taking in Syrian students to finish their university studies.
"We think many more countries can be doing that kind of thing," Edwards said.
Some additional pledges are expected to be announced at the Geneva talks, which UN Secretary-General Ban Ki-moon and UN refugee agency boss Filippo Grandi will address.