Farmers have been protesting across Europe over a range of grievances including what they say is unfair competition from Ukraine.

Many, particularly in Ukraine's neighbours, say they have been undercut by EU moves to open up "solidarity lanes", waive customs duties and bring in other measures to help Kyiv get its grain to market as it tries to stave off Russia's invasion.

In Poland, farmers began countrywide protests in February, blocking borders with Ukraine and disrupting ports and roads.

"Closing borders is never a good idea, even less borders with a neighbour in such need of connectivity," European Commissioner for Transport Adina Valean told Reuters in an interview late on Thursday.

"As long as the agreements are implemented correctly, there shouldn't be problems, and we are working on strengthening implementation," she added.

"In other words, we must check to ensure operators are not overstepping agreements, that they can only do bilateral operations, that ... they have the right to transit."

EU countries also stood to gain from the trade, Valean said.

Road exports to Ukraine from Poland, Romania and Slovakia had seen double-digit increases that exceeded the growth of goods flowing from Ukraine to those countries, she added.

That "shows there is a profitable exchange for border countries as well," Valean said.

Ukraine had exported more than 64 million tons of grain, oilseeds, and related products through the solidarity lanes from when they were established in May 2022 up until January, Valean said.

Three million tons of grains transited in January alone, she said, of which roughly 2.04 million tons went through Romania.

Grains arrive in Romania by road, rail and barge across the Danube river. While transit via Romania's Black Sea port of Constanta had slowed in January, road and rail exports to southern European countries were picking up speed as a result of EU-funded rail investments, Valean said.

But transit via the Danube river remained most relevant, with a minimum of 1.2-1.5 million tons of grain transiting the river monthly, and another 0.5-0.7 million tons of other products, such as fuels, going to Ukraine.

Valean said Ukrainian officials were talking with Romanian counterparts about installing three temporary floating buoys in the port of Constanta, which would add an additional 1 million metric tons to the port's monthly transit capacity.

(Reporting by Luiza Ilie; Editing by Andrew Heavens)

By Luiza Ilie