The EU's diplomatic chief Federica Mogherini said Tuesday she expected Lebanon's prime minister to return to the country "in the coming days" following his sudden resignation.
Saad Hariri quit during a TV statement from Saudi Arabia, prompting some observers to suggest it was done on Riyadh's orders and there have been claims he is under de facto house arrest in the oil-rich kingdom.
However, he has insisted he is free and plans to return home in "two or three days".
At a meeting with Lebanese Foreign Minister Gebran Bassil for talks in Brussels on Tuesday, Mogherini stressed the European Union's support for Lebanon's "stability, unity, integrity and sovereignty", according to a statement from her office.
"Close contacts will continue also with prime minister Hariri, through the EU's diplomatic channels: High Representative/Vice-President Mogherini expects him and his family to return to Lebanon in the coming days," the statement said.
After talks with EU foreign ministers on Monday, Mogherini demanded an end to outside interference in Lebanon -- which has been buffeted for decades by conflicts between bigger players in the region such as Iran and Syria.
Hariri's resignation came against the backdrop of mounting tensions between Sunni Muslim Saudi Arabia and Shiite Muslim Iran, which back opposing sides in power struggles in hotspots such as Syria and Yemen.