The EU has warned Romania that it could withhold more than 100m euros (£70m) of farm aid if the country does not reform its agricultural payments system.
Officials said they could hold back 25% of subsidies if Romania did not improve checks on how aid would be spent within a month.
Romania joined the EU earlier this year along with neighbour Bulgaria.
Farm aid payments to the two countries are scheduled to begin on 1 December and grow rapidly in coming years.
Romania "still has time to rectify the situation, but it is a matter of urgency", European Agriculture Commissioner Mariann Fischer Boel said on Wednesday.
Next year the EU is due to provide 443m euros (£306m) in agricultural subsidies to the Eastern European country.
That means about 110m euros (£76m) could be held back if the EU carries through with its threat.
Aid to Romania is meant to rise to more than 1bn euros (£690.000) by 2013.
Before the announcement an EU official described the Romania's farm payments system as a mess, according to the BBC's Oana Lungescu in Brussels.
In one case several farmers put in for EU money for a village pasture since they all grazed their cows on it.
Romanian Prime Minister Calin Tariceanu said the agency charged with checking subsidy claims by some 1.3 million farmers was under-equipped.
Even if the EU decides to withhold the payments Romanian farmers would receive the same amount of financial aid, but the Romanian government would have to pay the difference.
Ms Fischer Boel said Bulgaria was in line to qualify for the 202m euros due in farm aid for 2008 (£140m).