Heads of state or government of the member states of the European Union (EU) and the leaders of the EU institutions pledged to stand united in fight against terrorism, hours after attacks claimed by Islamic State killed more than 120 people in Paris.

"The European Union is deeply shocked and in mourning after the terrorist attacks in Paris," the leaders said in a joint statement, adding that their countries will stand united with the French people and the Government of France.

The leaders of 28 EU member states and the EU institutions, namely the European Council, the European Commission and the European Parliament, vowed to face terrorism threat with all necessary means and ruthless determination.

"Everything that can be done at European level to make France safe will be done. We will do what is necessary to defeat extremism, terrorism and hatred," they said, noting that "it is an attack against us all."

With a belief of "Good is stronger than evil," the leaders said this shameful act of terrorism will only achieve the opposite of its purpose, which was to divide, frighten, and sow hatred.

Meanwhile, the EU leaders decided to have a one-minute of silence in memory of the victims at noon on Monday across the European countries.

"We Europeans will all remember November 13th 2015 as a European day of mourning," the statement said.

A series of terror attacks in different locations in and around Paris killed at least 120 people and wounded some 200 others on Friday night, the deadliest violence in France since World War II.

In an online statement, the Islamic State claimed responsibility for the attacks and warned that France will be a target as long as it carries out military operation against Muslims.

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