BERLIN/KERCH, Crimea (Reuters) – Europe may need to impose tougher sanctions against Moscow following Russia’s seizure of three Ukrainian navy vessels and their crews at the weekend, an ally of German Chancellor Angela Merkel said on Tuesday.

Norbert Roettgen, a member of Chancellor Angela Merkel’s Christian Democratic Union, made the statement as Russia’s rouble recovered some of its losses from the previous day.

Markets are sensitive to developments that could trigger new Western restrictions and weaken Russia’s economy.

The U.S. State Department, the European Union, Britain, France, Poland, Denmark, and Canada have all condemned what they called Russian aggression after it opened fire on and seized three Ukrainian navy ships near Russian-annexed Crimea on Sunday. Moscow accuses the Ukrainian vessels of intruding into its territorial waters, which Kiev denies.

Merkel, an important voice in any future EU decision to impose more sanctions on Russia, on Monday spoke by phone to Ukrainian President Petro Poroshenko and said the situation needed to be de-escalated.

One option for the EU would be to add new companies or individuals to the bloc’s existing sanctions.

With relations still raw after Russia’s 2014 annexation of Crimea and its backing for a pro-Moscow insurgency in eastern Ukraine, the incident risks pushing the two countries towards a wider conflict.

The Russian Ministry of Foreign Affairs on Monday accused Ukraine of deliberately organizing what it called a provocation in the Black Sea by sending its ships through the Russian-controlled Kerch Strait with no advance warning and ordering them to ignore Russian orders to stop.

It said the Ukrainian action was coordinated with the United States and the EU to “create a pretext to ramp up sanctions against Russia”.

The Kerch Strait separates Crimea from mainland Russia. It is the only outlet to the Black Sea from the Sea of Azov, location of major Ukrainian ports.

‘CONFESSIONS’

A Reuters reporter at the Crimean port of Kerch where the captured Ukrainian vessels were being held said he could see traces of collisions and holes in the ships’ hulls.

A doctor at the local hospital said three Ukrainian servicemen were being treated there. An unidentified man prevented the Reuters reporter from entering or talking to them.

Russia’s FSB security service released video footage on Tuesday of some of the captured Ukrainian sailors admitting that their actions had been deliberately provocative and that they had ignored Russian orders to stop.

At least one of them appeared to be reading from a script. Ukrainian politicians said the sailors had been coerced, rendering their confessions meaningless.

Some of the sailors were expected to appear in a Crimean court later on Tuesday to answer charges that they illegally entered Russian waters. The FSB said it had information showing their mission had been pre-planned by the Ukrainian government and that two intelligence officers from Ukraine’s SBU security service had been on board to coordinate the provocation.

Vasyl Hrytsak, the head of the SBU, confirmed that his officers were on board to support the military and said one of them had been seriously wounded after Russian aircraft fired missiles at the Ukrainian vessels.

Ukraine, which on Monday night introduced martial law for 30 days in parts of the country it deems most vulnerable to an attack from Russia, said its ships did nothing wrong and had every right to proceed through the Kerch Strait.

The Kremlin said Ukraine’s decision to introduce martial law could escalate an already tense situation.