0709 GMT December 07, 2019
EU Commission chief Jean-Claude Juncker said it was the EU's biggest deal to date and, at a time of trade tensions between the US and China, showed that "we stand for rules-based trade", according to BBC.
Brazil's President Jair Bolsonaro said it was ‘historic’ and "one of the most important trade deals of all time".
Mercosur consists of Argentina, Brazil, Uruguay and Paraguay.
Venezuela is also a member but it was suspended in 2016 for failing to meet the group's basic standards.
The deal aims to cut or remove trade tariffs, making imported products cheaper for consumers while also boosting exports for companies on both sides.
It is set to create a market for goods and services covering nearly 800 million consumers, making it the largest in the world in terms of population.
The two parties began negotiating in 1999 but talks accelerated after US President Donald Trump's election in 2016. As a result EU-US talks were frozen.
The EU has also concluded trade agreements with Canada, Mexico and Japan since Trump's election.
However, the EU deal with Mercosur could see savings on tariffs that are four times as big as those made in the Japan deal, EU trade commissioner Cecilia Malmstrom said.
Narrow window to close the deal
Analysis by Daniel Gallas, South America business correspondent:
It is no small feat to close such a complicated deal at a time when free trade is under attack globally. Protectionism is clearly on the rise — with Brexit and the trade war between China and the US.
The deal could significantly change the way Europeans do business in countries like Brazil — which has one of the world's most closed economies. High tariffs have historically kept European competitors at a disadvantage against national industries.
Similarly, South American farmers will finally gain access to European food markets.
Europeans and South Americans had a narrow window to close this deal, as elections in Argentina later this year could potentially shift the mood against free trade, as is happening in other parts of the world.
What is the reaction?
Malmstrom said negotiations had begun 20 years ago to the day.
"They have been long negotiations — tough, difficult, and at least I have said many times 'we are almost there'. Now we are. This is a landmark agreement," Malmstrom said.
She said it sent a strong message that both the EU and Mercosur were in favor of ‘open, sustainable and rules-based trade’.
Speaking to reporters, Argentine Foreign Minister Jorge Faurie said Mercosur had hitherto been a ‘very closed commercial space’ but that the deal with the EU sent a "very clear message about where we are going".
Argentina's Secretary of International Relations Horacio Reyser said it would boost GDP, create jobs and attract investment.
However, the environmental group Greenpeace said the deal — and the likely growth in demand for Latin American agricultural products — amounted to a "disaster for the environment on both sides of the Atlantic".
Ahead of the deal's announcement, it said the agreement would lead to more destruction of the Amazon rainforest and attacks on indigenous peoples.
Cattle farming is already the biggest driver of deforestation, Greenpeace says.
Critics say Bolsonaro's plans to weaken environmental protections also threaten the Amazon.
What's in the deal?
The EU is already Mercosur's biggest trade and investment partner and its second largest for trade in goods, Reuters reported.
The EU wants to increase access for firms that make industrial products and cars — which are currently subject to tariffs of up to 35 percent — and also enable them to compete for public contracts in Mercosur countries.
Mercosur wants to increase exports of beef, sugar, poultry and other farm products.
In a statement, Brazil said the deal included eliminating tariffs on products such as orange juice, instant coffee and fruit.
Meanwhile, producers of other products such as meat, sugar and ethanol would have greater access to the EU market through quotas, the statement said.