Mark Zuckerberg has launched an implicit attack on Donald Trump, sharply criticising the Republican presidential front-runner’s rhetoric on immigration and trade by citing “fearful voices calling for building walls.”

In his keynote address to his company’s annual Facebook F8 developer conference in San Francisco, the Facebook founder appeared to compare Mr Trump’s candidacy to oppressive regimes who limit free speech by blocking access to the internet.

Mr Zuckerberg said he was “starting to see people and nations turning inward, against this idea of a connected world and a global community. I hear fearful voices calling for building walls and distancing people they label as others. For blocking free expression, for slowing immigration, reducing trade, and in some cases around the world even cutting access to the internet.”

While he did not name Mr Trump directly, there was little question that he was the target of Mr Zuckerberg’s remarks, specifically the property mogul’s plan to construct a wall the length of the US-Mexican border. Mr Trump’s main Republican rival, Texas Senator Ted Cruz, has also vowed to build a border wall should he be elected President.

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Mr Trump and Mr Cruz have both also pledged to deport millions of undocumented immigrants living in the US. Mr Zuckerberg, by contrast, has advocated repeatedly for immigration reform and backed a plan to expand a visa programme for skilled immigrants of the sort who are regularly hired by Silicon Valley firms.

The Facebook CEO said the social network’s mission was to “connect the world” with projects including Aquila, a high-altitude aircraft that can fly unmanned for months at a time, beaming internet access to isolated regions in the developing world. “We’ve gone from a world of isolated communities to one global community and we are all better off for it,” Mr Zuckerberg said.