The planned execution in Florida of Manuel Valle, a 61-year-old Cuban convicted of the 1978 murder of a cop, was on hold Wednesday as the US Supreme Court weighed petitions for a last-minute stay. Valle had been scheduled to be put to death at 4:00 pm (2000 GMT) Wednesday. The execution was delayed pending Supreme Court review of requests for a stay, said Jo Ellyn Rackleff, a spokeswoman for the Florida Department of Corrections. Though he has been on Florida\'s death row for decades for the 1978 murder of Louis Pena, a 41-year-old police officer, Spain also sought to get the United States to stop the execution arguing that Valle likely was eligible for Spanish nationality. Valle\'s execution is scheduled just one week after the highly controversial high-profile execution of Troy Davis, who went to his death proclaiming his innocence in the murder of a policeman in the state of Georgia. Spain\'s envoy to Miami told AFP that Madrid had intervened in the case because it opposes the death penalty. The US and Cuba do not have full diplomatic ties. Valle could become the first inmate put to death in Florida using sodium pentobarbital in US lethal injections, following domestic shortages of the previously used anesthetic sodium thiopental. Danish drugmaker Lundbeck, which produces pentobarbital under the brand name Nembutal for treatment of epilepsy, said in July it would restrict distribution of Nembutal after learning that it was being administered by several states as part of a three-drug cocktail used to execute death row inmates. On Monday a neurologist submitted a petition to the Florida Supreme Court requesting a halt to Valle\'s execution, claiming that use of pentobarbital in lethal injections is illegal because the controlled substances act prohibits its use for non-medical purposes. The court dismissed the suit on Tuesday. Petitions requesting a stay of execution and a review of the case have been submitted to the US Supreme Court, Valle\'s lawyer Suzanne Myers Keffer said earlier. Use of sodium pentobarbital would cause \"substantial harm\" to Valle, Keffer told AFP, noting this was one of the issues raised with the nation\'s highest court. Other points made to the court include that Valle was placed on death row in an \"arbitrary manner,\" never received \"full clemency proceedings\" and that his time served is \"cruel and unusual punishment,\" she said. London-based rights group Reprieve said Valle has not benefited from consular advice because Florida did not inform Cuba of his arrest. The Cuban Interests Section in Washington declined to comment on the case when contacted by AFP. Davis\'s case galvanized global efforts to end capital punishment, drawing support from high-profile figures including former US president Jimmy Carter, South Africa\'s bishop Desmond Tutu and Pope Benedict XVI. Davis maintained his innocence until his dying breath and there was a flood of international condemnation after he was put to death by lethal injection, despite doubts about his guilt for the 1989 slaying of a white police officer.