He said that the crisis is the whole continent’s battle and promised to use any legal means to quash secession.
In an interview with El Pais, Mr Rajoy said: “Spain is not going to divide and national unity will be maintained.
“We are going to stop independence from taking place.”
He went on to insist the crisis was Europe’s battle, as well as Spain.
The PM said the referendum was part of the rising populism across Europe leading to figures “like Marine Le Pen and Nigel Farage” gaining popularity.
He added: “Which is why I say that this is Europe’s battle and… I encourage Europe to continue with what it’s doing which is defending the unity of its nations.”
Although he offered no concrete plans for how to stop Catalan independence going ahead, the Spanish leader said that they would “use all of the instruments that the legislation gives us”.
He also refused to rule out invoking Article 155, which allows the Spanish government to step in and take control of an autonomous region if it “does not fulfil the obligations imposed upon it by the constitution or other laws, or acts in a way that is seriously prejudicial to the general interest of Spain”.
It has never been used before.
He also slammed Carles Puigdemont, the Catalan leader, for not considering the consequences of the “illegal” referendum.
Businesses have begun moving their headquarters out of the region and the separation likely to have a knock on effect on tourism and Catalonian debt, said Mr Rajoy.
He also raised hope of dialogue between leaders in Madrid and Barcelona but blasted Carles Puigdemont saying it was difficult to negotiate with someone who “doesn’t have more than one objective and is unable to move a single centimetre”.