* Several Belgian-Dutch border crossings blocked

* Polish farmers threaten closure of Ukraine border

* Greece promises extra aid to grieving farmers

* French government pledges more farm measures

BRUSSELS, Feb 2 (Reuters) - Farmers blocked the Dutch-Belgian border on Friday and occupied roads in Greece while their Polish peers announced plans to shut border crossings with Ukraine as protests for fairer prices and less red tape spread across Europe.

Farmers' protests have erupted in several countries, exposing anger about low prices for produce, rising costs, import of cheap foodstuffs from and constraints imposed by the European Union's drive to fight climate change.

While French farmers started lifting blockades on Friday after the government made further concessions, Belgian and Dutch farmers blocked motorway border crossings between their countries.

At one roadblock, Dutch pig farmer Johan Van Enckevort, 25, warned the European Union and Dutch politicians holding cabinet formation talks not to ignore farmers' needs.

"We have very nice products here in the EU and we want to continue to make those products. But it has to be done in a fair way, in a decent way and not with so many rules. It just can't go on like this," he said.

The frustration came to a head in Brussels this week, where farmers threw eggs and stones at the European Parliament and set off fireworks as they demanded EU leaders at a summit nearby do more to help them.

"The Common Agricultural Policy has gradually become a Common Ecological Policy, without any recognition for us food producers," Belgian farmers union ABS said in a statement.

At the North Sea port of Zeebrugge in Belgium - which handles car imports and some fresh produce from the United Kingdom and elsewhere - farmers continued to prevent trucks from entering or leaving.

Carmakers sending deliveries through Zeebrugge include Tesla , BMW, Mercedes, Hyundai and Volvo, a port spokesperson said, adding that the port's capacity was fast filling up with vehicles stuck on the quay. Around 2,000 trucks were backed up outside the port.

Polish farmers' union Solidarity on Friday announced a general strike starting next Friday with a blockade of border crossings between Poland and Ukraine.

"Our patience has run out," it said, referring to the import of Ukrainian produce.

In Greece, farmers have set up blockades in the centre and north of the country, calling for a permanent exemption on diesel taxes and faster compensation for flood-related losses.

In Portugal, where farmers used tractors to block at least three roads linking Portugal to Spain on Thursday, one road in the southern region of Alentejo near the border with Spain remained blocked on Friday, and farmers staged slow marches in several places across the country.

Spanish farmers said earlier this week they would take to the streets in February in protest against strict European regulations and lack of government support.

French farmers, meanwhile, were on Friday dismantling roadblocks at dozens of sites across France, including several highways leading into Paris, pausing their protests after receiving more government pledges.

The French farmers said President Emmanuel Macron's government now needed to act fast on its pledges, which have included scrapping plans to reduce tax discounts on tractor diesel, an easing of pesticide regulations, a pause on new fallow land rules, and more safety checks on food imports.

Farmer Guillaume Chantereau, 31, who grows cereals and raises chickens for eggs, said a lot of work was waiting for him at the farm, but added that he would be back on the barricades if the government does not deliver.

"For now, we ease off, but we will not give up. We are used to hearing nice speeches, and these are not always respected, so better watch out," he said.

(Reporting by Charlotte Van Campenhout and Christian Levaux in Belgium, Noemi Olive in France, Anna Wlodarczak-Semczuk in Poland and Andrey Khalip and Patricia Rua in Portugal; Writing by Geert De Clercq; Editing by Varun H K, Jamie Freed and Emelia Sithole-Matarise)