Ashton issued a statement Monday through her spokesman's office condemning Sunday's attack in Sinai that left four people dead, including three South Korean tourists. She said all perpetrators of the attack must be brought to justice.
"[Ashton] reaffirms the commitment of the European Union to support the stability and security in Egypt to achieve a sustainable democracy and a better life for all Egyptians," the statement added.
The European Union has expressed concern about political developments in Egypt since a popular uprising unseated former President Hosni Mubarak in 2011.
Since Mubarak's resignation in 2011, Egyptians elected the Muslim Brotherhood's Mohamed Morsi, though he was removed from office by the Egyptian military in July.
Ahram Online, an Egyptian news website, reported Monday the Egyptian military raided suspected terrorist sites in Sinai. No group claimed responsibility for the weekend attacks.