The European Union extended by six months an existing set of sanctions against Russian and pro-Russia separatist officials because of the continued fighting in eastern Ukraine and was planning further action, officials said Thursday.

"We have shown that the EU is ready to take further measures," EU foreign affairs chief Federica Mogherini said.

All EU foreign ministers at Thursday's meeting in Brussels, including the new Greek minister, agreed on the extension, Dutch Foreign Minister Bert Koenders said, calling it a "strong signal toward Russia."

There had been wariness whether the new radical left-wing government in Greece would immediately fall in line with the actions against Russia. France and some others said that while firmness was essential, room for negotiation had to be kept open.

Leaders will hold a summit on Feb. 12 to discuss further action.

Last March, the EU imposed the first visa bans and asset freezes against officials linked to Russia's annexation of southern Ukraine's Crimean Peninsula. The measures were due to expire this March, and Thursday's decision will extend them until at least September.

Pressure for more action has been building since last weekend's attacks on Mariupol, when rockets crashed into a densely populated eastern district, killing 30 and wounding several dozen. International observers said a preliminary assessment indicated the attack had been mounted from rebel-held areas.

Since Russia's annexation of Crimea, the EU has steadily increased restrictive measures. In July, the EU imposed economic sanctions which, combined with the drop in oil prices, have stung Moscow.

Mogherini said that on top of Thursday's decision to extend the first batch of sanctions, the EU was also preparing a list of new officials to be put on the visa ban and asset freeze program, which could be confirmed as soon as Feb. 9.

If the situation on the ground doesn't improve, further measures were to be drawn up before the EU summit of government leaders on Feb. 12.

"We hope that this can help in putting pressure, in particular on Russia, to make positive steps and prevent the negative steps that we have seen in the recent days," Mogherini said.

Meanwhile, Russia has extended its walkout from Europe's human rights watchdog after again losing its right to vote over the conflict in eastern Ukraine. The Parliamentary Assembly of the Council of Europe, meeting in the French city of Strasbourg on Wednesday, voted to renew sanctions against Russia at least until April. Russian delegate Alexei Pushkov said Thursday that his delegation's walkout would continue the rest of the year.