"I believe that we have learned in these 30 years that the solution has to be imposed from outside because the two parties will never be able to reach an agreement," he told an event in Lisbon, warning also that "if this tragedy doesn't end soon, the entire Middle East might end up in flames".
The war reached into Lebanon on Tuesday with the killing in Beirut of the Hamas deputy leader, Saleh al-Arouri, in a drone strike. Israel has neither confirmed nor denied that it killed al-Arouri.
The assassination was a further sign that the nearly three-month war between Israel and Hamas was spreading across the region, drawing in the occupied West Bank, Hezbollah forces on the Lebanon-Israel border, and even Red Sea shipping lanes.
"What happened yesterday with the death of one of the leaders of Hamas is yet another factor that could push the conflict to escalate," Borrell said, adding he had plans to visit the Middle East, including Lebanon, to "explore ways out" of the conflict.
Borrell also said he would present to the EU member states a proposal to create a mission to contribute to security in the Red Sea. The proposal is set to be presented on Thursday and would require unanimity among member states for it to go ahead, he said.
(Reporting by Catarina Demony and Miguel Pereira; Editing by Andrei Khalip and Nick Macfie)
By Catarina Demony
