Leaders agree 2050 climate neutrality - without Poland

"We took this decision with respect for many concerns of different countries because we know that it is important to take into consideration the different national circumstances, and also different starting points," Michel told reporters.

The decision follows the unveiling of the new European Green Deal by the EU Commission on Wednesday, which includes a climate law based on a climate-neutrality target for 2050. But member states will only have to reach a qualified majority to pass it into law.

According to the Intergovernmental Panel for Climate Change (IPCC), achieving carbon neutrality by 2050 is essential to limit global warming to 1.5 degrees - the main objective of the UN Paris Agreement.

However, Poland had tried to postpone the date to 2070 earlier on Thursday.

Polish prime minister Mateusz Morawiecki said that the negotiations were "very difficult" and that his country will be "reaching climate neutrality at its own pace".

Currently, around 80 percent of Poland's power production is provided by coal, although the country aims to cut it to half by 2040.

"We acknowledge that the transition is a big one for Poland," said the president of the commission Ursula von der Leyen, adding that although Poland needs time to go through the details, this will not change the timeframe of the commission.

According to German chancellor Angela Merkel, "there is no division of Europe into different parts, but there is a member state that still needs a bit more time".

However, Hungarian prime minister Viktor Orban insisted that extensive "financial guarantees" are required for those countries whose energy production deeply depends on fossil-fuels.

"We cannot allow Brussels bureaucrats to have poor people and poor countries to pay the costs of the fight against climate change," he said.

EU countries tried to reach a deal on zero emissions by 2050 in June, but Poland, Hungary and the Czech Republic held out, wanting to see financial incentives.

Nuclear disagreement

Those three countries were still in opposition when the summit started, although the Czech Republic and Hungary were on board once they managed to include a mention in the official conclusions that member states can use nuclear energy to reduce their emissions.

EU leaders agreed on "the need to ensure energy security and to respect the right of the member states to decide on their energy mix and to choose the most appropriate technologies".

Despite opposition from Austria, Luxembourg and Germany, "some member states have indicated that they use nuclear energy as part of their national energy mix".

"It was a long and difficult struggle," said Austrian chancellor Brigitte Bierlein. "Every country can decide its national energy mix. For Austria, nuclear energy is not a safe and sustainable source of energy."

According to Luxembourg's prime minister, Xavier Bettel, "every country is free to decide what kind of energy to produce," but nuclear energy should not be financed with the contributions of the European taxpayers.

However, France, Britain and several central-eastern European countries defend the role of nuclear power in the transition towards a more climate-friendly Europe.

More than 60 percent of electricity in France is produced in nuclear power plants. According to French president Emmanuel Macron, "nuclear energy is part of the transition".

"For countries that must leave coal, it is clear they cannot pass from one day to another to renewable energy. It is not possible because renewable energy is intermediary energy," he said.

Achieving climate-neutrality in the Czech Republic "without nuclear energy is not possible", said its prime minister Andrej Babiš, who believes that "nuclear energy is clean energy".

"If we want to achieve climate-neutrality, we have to understand that every member state has a different energy mix and to reach climate neutrality has also different costs," he added.

The commissioner for the Green Deal, Frans Timmermans, said on Thursday at the UN climate conference (COP25) in Madrid that "there is, by no means, a way that you can say that nuclear is sustainable energy".

"I have no opposition in principle against nuclear energy, but I don't think, in the long term, that there is a future since it's not sustainable energy," Timmermans added.