Convoys of tractors disrupted traffic around the Spanish capital on Wednesday as farmers protesting against what they see as excessive red tape and insufficient state aid converged in downtown Madrid to march towards the Agriculture Ministry.

Farmers have been protesting for weeks across European countries, most recently including Poland, Greece and the Czech Republic. They all call for a reduction of bureaucracy linked to the European Union's Common Agriculture Policy and a loosening of the bloc's environmental rules.

As they waited for five columns of tractors to reach the gathering point at the central Independence Square, protesters wearing yellow vests waved Spanish flags and rang cow bells there while blaring music from loudspeakers.

Traffic around the Puerta de Alcala monument ground to a halt, with several buses unable to continue their routes as protesters crowded the streets.

Some farmers complained that police were preventing tractors from entering Madrid. The government said that 500 tractors had been allowed entry - as that was the figure given by organisers when requesting authorisation for the protest - while an additional 150 vehicles were blocked from the city.

Two of the five columns had already arrived, the government said, adding that the only incident of note was the blockade of the A42 motorway connecting Toledo to Madrid, which had been broken up by the police.

Lucia Risueno, a 52-year-old vineyard farmer from the Castille-La Mancha region, said that authorities had failed to help the sector and called for fairer prices.

"I have the same expenses but I'm making half as much, so we can't go on like this," she told Reuters, adding there was no limit to the protests until the government implemented strong measures to aid farmers.

Adolfo Albaladejo, 54, said he was fighting to ensure agriculture does not disappear from his country.

"The Spanish countryside wants protectionism. We want to protect our products and be competitive," he said. (Reporting by Catarina Demony, Guillermo Martinez, Antoine Demaison and Marco Trujillo; Writing by David Latona; Editing by Alex Richardson)