The European Union executive has said there has been an increase in the number of people arriving in Europe without a genuine claim to asylum.
The statement comes as EU countries around the continent grow increasingly nervous overthe migration crisis.
The 28-nation bloc has all but failed to curb or control the influx of refugees and migrants, with more than one million arriving in Europe last year, mainly via Greece and heading towards the EU's biggest economy, Germany.
More than 54,500 people have already reached Europe by sea this year, including 50,668 through Greece, according to data from the United Nations Refugee Agency (UNHCR).
That is despite winter weather making the journey even more perilous, a fact highlighted by the UNHCR saying 235 people were dead or missing already in 2016.
24 migrants, including ten children, drowned when their boat sank off a Greek island close to Turkey today.
Much of the EU debate on how to handle the influx has focused on distinguishing people fleeing war and thus eligible for international protection from labour migrants seeking better lives without being under immediate threat.
"Indeed we have seen that the numbers of people arriving in Europe who don't have a genuine claim to asylum have been rising slightly," a spokeswoman for the European Commission told a regular news briefing.
While the overall number of arrivals is low compared to some 500 million people living in the EU, the uneven distribution among member states has put major pressure on public and security services in some states.
It has also fueled support for anti-migrant nationalists and populists across the bloc.
The EU border agency Frontex also said the number of Syrians arriving on Greek islands had declined in recent months, while Iraqi arrivals had risen.
"The percentage of declared Syrians among all of the migrants landing on the Greek islands has fallen considerably in the last several months," Frontex said.
The agency added that some 39% of those arriving in Greece in December were Syrians, compared to 43% in November and 51% in October.
The shifting numbers partly reflect how registration and identification of migrants has improved in Greece over the last quarter, meaning fewer people pass under false nationality.
Syrian nationality has been a common answer to the question of origin as people fleeing the five-year-old civil war in the Middle Eastern country are seen as standing a higher chance of successful asylum applications.
In fresh signs of growing nervousness with the migration crisis, Denmark has passed news laws - criticised by rights groups - aimed at deterring refugees and Sweden announced it would likely deport up to a half of the record 163,000 asylum seekers that entered the country in 2015.
Finland went further than its Scandinavian neighbour in percentage terms, saying it expected to expel early 20,000 migrants out of the 32,000 who sought asylum last year.
Swedish minister forecasts expulsions in interview
Swedish Interior Minister Anders Ygeman said he estimated about 60,000 to 80,000 of the people who sought asylum last year would be expelled and either leave voluntarily or be forcibly deported.
The government fears many of those will go into hiding, business daily Dagens Industri reported, and police are increasing their work to find and expel those.
"We have a big challenge ahead of us. We will need to use more resources for this and we must have better cooperation between authorities," Mr Ygeman was quoted as saying.
This week, Prime Minister Stefan Lofven promised more resources for police to deal with the increased workload because of the refugee situation.
Sweden reversed its open doors-policy on immigration late last year and has introduced border controls and identification checks to stem the flow of asylum seekers.