The European Union is ready to increase sanctions on Russia but the priority is to bolster the fragile ceasefire agreed in Minsk, EU foreign policy chief Federica Mogherini said on Friday.

Mogherini, who is attending a meeting of EU foreign ministers in Latvia, said that despite some signs of improvement on the ground there was no question of the EU easing sanctions now.

"So far the ceasefire has started, it’s not perfect with some violations still, but for sure the trend is a positive one," Mogherini said, adding that before the meeting she discussed this issue with Ukrainian President Petro Poroshenko during a telephone conversation.

"They [the sanctions] will not be lifted until something really good happens on the ground and on the other hand we are always ready to increase the pressure if needed," Mogherini said.

She said that for the ceasefire to be upheld it was crucial that monitors from the Organization for Security and Co-operation in Europe (OSCE) have their mission strengthened.

"We need ... to strengthen the OSCE mission that is on the ground now," Mogherini said.