European Union officials were not immediately available to give further details of the ambassadors' meeting
"Extremely worried for arrest of @hdpdemirtas & other @HDPgenelmerkezi MPs. In contact with authorities. Called EU ambassadors meeting in Ankara," Mogherini tweeted.
European Union officials were not immediately available to give further details of the ambassadors' meeting.
EU relations with Turkey have been badly strained by the migrant crisis but they took a sharp turn for the worse after President Recep Tayyip Erdogan embarked on a massive purge in the aftermath of a failed coup in July.
Mogherini, other top EU officials and many of the European Union's 28 member states have all repeatedly urged Erdogan not to breach human rights in the crackdown.
They have warned also that any re-introduction of the death penalty would immediately halt Turkey's already difficult accession talks as it pursues membership of the bloc.
Earlier Friday, Turkish police detained the two co-leaders of the Peoples' Democratic Party (HDP) and several other MPs.
Selahattin Demirtas was detained at his home in the southeastern city of Diyarbakir while the co-chairperson Figen Yuksekdag was held in Ankara as part of a terror investigation, the state-run Anadolu news agency said.
Their detention appeared part of a large-scale operation against the HDP, which is the third largest party in the Turkish parliament.
Reports said the pair were accused of spreading propaganda for the outlawed Kurdistan Workers Party (PKK).
Hours after the arrests, a suspected car bomb killed one person and injured 30 in Diyarbakir.