Austria's Foreign Ministry says it has been unable to contact the nine foreigners working for Austrian oil services company VAOS who were kidnapped by the Islamic State group in Libya.

Michael Linhart, a senior ministry official, said "there is currently no sign of life nor proof of death" from the workers, who include an Austrian, a Czech and seven non-EU citizens.

Security teams retook the site after the attack Friday at the al-Ghani oil field. In a statement Sunday, Linhart blamed the attack on IS affiliates from nearby Sirte, who "are known to have been behind the brutal execution of a group of Coptic Christians in the past."

He said Austria is in contact with Libyan authorities and "all friendly nations and organizations that have special expertise in this region."