Russia's President Vladimir Putin said Thursday he was ready to prolong a unilateral ceasefire in Aleppo, after tough talks in Berlin where the leaders of Germany and France refused to rule out sanctions against Moscow.
Putin said he told the European leaders that Russia was "intending to extend as far as possible" a halt to its air raids in Syria's second city, in order to allow civilians and rebels to leave the devastated city.
The concession came as French President Francois Hollande starkly condemned the bombing as "a war crime" and German Chancellor Angela Merkel described it as "inhumane and cruel".
The leaders of Europe's two biggest economies also dangled the threat of sanctions, hours ahead of an EU summit where Russia's role in Syria is set to be discussed.
A pause in Russian and Syrian strikes on Aleppo held for a second day Wednesday, ahead of the brief unilateral ceasefire due to start at 0500 GMT on Thursday.
Ahead of the talks in Berlin, Moscow announced it would prolong the truce from eight to 11 hours, and said Syrian and Russian warplanes were giving Aleppo a wide berth.
But its plan has stirred scepticism in the West and the United Nations said it would be insufficient to allow humanitarian aid to reach encircled Aleppo inhabitants.
Amnesty International released new satellite images Wednesday showing more than 100 sites were hit in two weeks of bombing raids in the city.
The rights group said there was evidence Russian-made cluster munitions, banned under international conventions, had been used in civilian areas of eastern Aleppo in recent weeks, "part of a deliberate military strategy to empty the city of its inhabitants and seize control".
Meanwhile, the Syrian army said that a planned humanitarian truce beginning in eastern Aleppo on Thursday would extend to three days, the state news agency SANA reported late Wednesday.
- Bombing a 'war crime' -
Wednesday's visit was Putin's first to Berlin since Russia annexed the Crimea peninsula from Ukraine in 2014 and sent relations with the West to a low.
Moscow's backing for President Bashar al-Assad's regime in its war with a wide range of rebel groups, including with air strikes in the divided northern city, has furthered soured ties with Europe and the United States.
Describing the late night talks as "very tough", Merkel said they "gave Germany the clear chance to define what constitutes a war crime. Bombardments are inhumane and a cruel experience for the people".
Hollande told Putin bluntly that "what is happening in Aleppo is a war crime, one of the first demands is that the bombardments by the regime and its (Russian) backers must end".
The European leaders also vowed to keep up the pressure, warning of possible sanctions.
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"Everything that can constitute a threat can be useful," Hollande said, as Merkel added that "we cannot remove this option".
EU leaders meeting at a summit in Brussels on Thursday are expected to up the ante by condemning Moscow over the attacks on civilians in Aleppo, according to a draft statement obtained by AFP.
- Thursday truce -
Thursday's brief truce is expected to see all fighting stop to allow civilians and rebels to exit opposition-held districts via six corridors.
Senior Russian military official Sergei Rudskoi said Russian and Syrian planes were keeping 10 kilometres (six miles) from Aleppo, a city home to an estimated 250,000 people and which has been under near-continuous government siege since July.
AFP's correspondent in east Aleppo said although clashes between rebels and pro-government forces involving heavy artillery continued in several neighbourhoods, the pause in air strikes held on Wednesday.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said pro-regime fighters were pressing their ground assault in the Old City as they vied to shift the front line.
Russian and Syrian bombardment had been providing air cover for a government offensive that started on September 22 aimed at seizing the city's east, held by rebels since 2012.
According to Moscow, once the pause begins six corridors out of the city would open for civilians with another two -- via the Castello Road in the north and Souk al-Hal in the city centre -- designated for rebels.
The UN dashed hopes however that a prospective Aleppo truce could allow humanitarian aid to reach civilians.
"Before we can do something really meaningful... we need assurances from all parties" over a lasting ceasefire, a spokesman for the UN's humanitarian agency said in Geneva.
Rebel groups have indicated they will not abandon their posts and, with Aleppo encircled by pro-government forces, many civilians fear falling into the hands of the regime.
- 'Managing international pressure' -
Syria analyst Thomas Pierret, of the University of Edinburgh, said the halt in Russian air strikes was about Moscow "managing international pressure".
"Russia is periodically trying to mitigate tensions with the West on Aleppo through such initiatives. This is the continuation of war by diplomatic means," he said.
Five years of diplomatic initiatives to put an end to Syria's conflict have failed, but over the past week world powers have made new efforts to reach a lasting truce.
Besides the Berlin summit, talks were also held Wednesday in Geneva between Russian, US, Saudi, Qatari and Turkish officials on the efforts to distance Syrian opposition fighters from jihadists.