BRATISLAVA (Reuters) - Slovakia will file a lawsuit by Dec. 18 challenging the European Union's planned quota system that will see 120,000 asylum seekers distributed among member countries, Prime Minister Robert Fico said on Sunday.

Slovakia, the Czech Republic, Hungary and Romania opposed the mandatory quotas for redistributing migrants from Italy and Greece, but were outvoted at a meeting of EU interior ministers in September.

The EU has struggled to find a common approach on how to deal with a surge in migrants and refugees fleeing conflict and poverty in the Middle East, Africa and Asia. Germany expects that more than a million refugees to arrive this year. 

Slovakia, which is due take in 802 migrants under the scheme, immediately said it would challenge the decision, arguing it had no power to keep migrants in if they wish to move on to Germany and other richer EU member states. Slovakia has only received 154 asylum requests this year.

Hungary has also sought to challenge the quotas and its parliament this month authorized the government to take action. The Czechs and Romanians have said they will not sue.

Fico said on Sunday Slovakia would meet the Dec. 18 deadline at the European Court of Justice. 

"We will take the legal action at a court in Luxembourg sooner, we will talk about it this week," Fico said in a televised debate. 

Fico, who is seeking reelection in March, said in October he did not fear the quota system would be implemented against Slovakia's will as it was not technically enforceable.

(Reporting By Tatiana Jancarikova; Editing by Raissa Kasolowsky)