OTTAWA (Reuters) - Public security concerns after the Paris attacks were part of the reason Canada pushed back its end-year deadline for accepting 25,000 Syrian refugees, Prime Minister Justin Trudeau said on Wednesday.

Clothing donated for an expected influx of Syrian refugees is sorted by volunteers for size and gender at a theatre rehearsal space in Toronto November 24, 2015. REUTERS/Chris Helgren

The federal government on Tuesday announced it was aiming to welcome the refugees by the end of February rather than Jan. 1 and said all necessary security checks would be carried out in the region rather than in Canada.

Critics said the initial plan was too ambitious and would lead to rushed security procedures, especially in the wake of the Nov. 13 attacks in Paris for which Islamic State claimed responsibility.

“One of the things that changed with Paris was the perception that Canadians had ... (they) had a few more questions,” Trudeau told reporters in London when asked about the new deadline.

Canada will spend up to C$678 million ($510 million) over six years flying in the refugees from Turkey, Syria and Jordan and then helping resettle them. The first flight is due to leave from the region early next month.

Aid groups preparing to resettle the refugees in Canada welcomed the new timeline, especially given thin resources on the ground after a decade of cuts to refugee flows by the previous Conservative government.

“Most of the organizations and institutions doing the welcoming will be happy to have a few extra weeks to get ready,” said Janet Dench, executive director of the Canadian Council for Refugees, a high-profile umbrella group for the settlement and sponsorship of refugees and immigrants.

While Canada has welcomed big groups of refugees in the past - including 5,000 Kosovars in 1999 and 60,000 Vietnamese between 1979 and 1980 - the Conservative government that preceded Trudeau’s Liberals, who won an election in October, shifted focus to skilled immigrants who met strict economic criteria rather than refugees.

In 2014, 23,286 refugees were admitted to Canada, down from 35,775 in 2005, according to government data.

The move away from refugee resettlement meant many agencies dedicated to the task of helping refugees find housing, jobs, schooling, language classes have cut staff, programs and services for a decade.

“In last 10 years we’ve been seeing a lot of cuts to the sector, a lot of cuts - anywhere between 2 percent of the budget to 100 percent of the budget, which was quite traumatizing, very disheartening,” said Huda Bukhari, executive director of the Arab Community Centre of Toronto.