ATHENS — European foreign ministers on Saturday said they fully supported efforts by US Secretary of State John Kerry to keep Middle East peace talks alive as tension mounted on both sides.

“We support the efforts of Secretary of State Kerry,” EU foreign affairs chief Catherine Ashton said at the close of a two-day meeting in Athens.

Kerry has labored lately to bring Palestinians and Israelis back from the brink.

On Friday he warned from Morocco that there were “limits” to the time and effort the United States could devote to the process “if the parties themselves are unwilling to take constructive steps.”

But Palestinian Authority President Mahmoud Abbas has rejected Kerry’s appeals to withdraw applications he signed on Tuesday to adhere to 15 international treaties in pursuit of recognition for the Palestinians’ promised state.

And Israeli Prime Minister Benjamin Netanyahu has likewise ignored calls to refrain from hardline moves, and has reportedly asked his officials to draw up reprisals.

“Kerry’s initiative is without doubt in a critical phase,” German Foreign Minister Frank-Walter Steinmeier said on Saturday.

“The radicals on both sides seem to start to prevail…we have to prevent that,” Steinmeier told reporters.