BARCELONA (Reuters) - Four jailed Catalan separatist leaders currently on hunger strike sent letters to more than 40 European heads on Monday to protest what they see as mistreatment by the Spanish courts.

The dispute between Catalonia’s independence-seeking regional government and Madrid has worsened in recent weeks as negotiations have reached an impasse. Pro-independence protests are planned across Catalonia on Friday.

“We suffer from a judicial process that severely violates our fundamental rights, including the right to the presumption of innocence,” the Catalan leaders wrote in the letter, which was sent to more than 40 European heads of state and government.

Spain’s courts are unduly delaying their appeal demands to prevent the separatists appealing at the European level, the Catalan leaders said.

The four signatories went on hunger strike earlier this month to protest their treatment by the Spanish judiciary, though they have no intention of starving themselves to death, one told Reuters last week.

A total of nine Catalan leaders are in jail awaiting trial for their role in the region’s failed bid to split from Spain last year. If convicted, they face decades in prison on charges including misappropriation of funds and rebellion.

Prime Minister Pedro Sanchez and his cabinet will travel to Barcelona on Friday for a meeting to be held amid high security as pro-independence groups have announced plans to hold protests and block transport in the region.