UK govt vows further sanctions, summons Iran envoy over protests

Mass rallies have erupted across the country demanding an end to the clerical system in power since 1979, triggering a crackdown that activists say has killed at least 648 people during an internet blackout.

Cooper told MPs in parliament that the United Kingdom will bring forward legislation "to implement full and further sanctions and sectoral measures" on Iran.

Cooper noted London has already sanctioned key players in Iran's oil, energy, nuclear and financial systems but would now target those in finance, energy, transport, software and "other significant industries which are advancing Iranian nuclear escalation".

She said the UK would work with the EU and others on any "additional measures".

Cooper said she had ordered the ambassador be summoned "to underline the gravity of this moment and to call Iran to answer for the horrific reports that we are hearing."

She added that she fears the reports "may underestimate the full scale of the horror" in Iran, and warned the world was watching.

"The UK will continue to confront the regime's lies, to call out its repression and to take the steps necessary to protect the UK's interests," she said.