"We, developed and developing countries together, will defend the Paris Agreement"

* EU, ACP group reaffirm backing for Paris Agreement

* Canete says climate pact "irreversible"

* U.S. President Trump considering whether to pull out

BRUSSELS/BONN, Germany, May 18 (Reuters) - The European Union will provide 800 million euros ($891 million) to help 79 African, Pacific and Caribbean (ACP) nations implement a global deal to combat climate change.

The EU support comes as U.S. President Donald Trump is considering whether to carry out a campaign threat to quit the landmark Paris Agreement, which agreed in 2015 to shift the economy away from fossil fuels.

"We, developed and developing countries together, will defend the Paris Agreement," European Climate Commissioner Miguel Arias Canete said on Thursday.

As a sign of closer cooperation with the ACP group "the EU has announced support of 800 million euros up to 2020, with around half earmarked for climate action," the European Commission said in a statement.

It said the EU will also provide 3 million euros to support Fiji, which will oversee United Nations negotiations in 2018. It did not detail how the rest of the money would be spent.

Trump has said he will decide on the Paris Agreement after a Group of Seven summit in Italy on May 26-27.

Canete called the Paris Agreement "irreversible and non-negotiable" as almost 200 nations attend U.N. talks in Bonn on a detailed "rule book" for the deal. ($1 = 0.8975 euros) (Reporting by Alissa de Carbonnel and Alister Doyle; editing by Alexander Smith)

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