World leaders on Friday reacted with concern and regret to the UK’s historic vote to leave the European Union.

US President Barack Obama said the United States respects the decision and that the special relationship between Washington and London will endure.

Obama had strongly urged that the UK to remain in the EU, but said in a statement that the UK and the European Union will remain "indispensable partners of the United States" even as they begin negotiating the future of their relationship.

In Beijing, Foreign Ministry spokesperson Hua Chunying told a routine press briefing that China is still keen to strengthen its ties with Britain, but noted that its decision to leave the EU will have significant ramifications.

"The impact will be on all levels, not only on China-Britain relations. As to what kind of impact there will be, I believe all sides will calmly and conscientiously assess this," the spokesperson said.

"China supports the European integration process and would like to see Europe playing a positive role in international affairs. We have full confidence in the prospects for the development of China-EU ties," Hua said.

French President Francois Hollande said, "I profoundly regret this decision for the United Kingdom and for Europe, but the choice is theirs and we have to respect it."

German Chancellor Angela Merkel expressed "great regret" over the result and warned that Europe shouldn't draw "quick and simple conclusions" that would create further division.

Scottish First Minister Nicola Sturgeon said it is "highly likely" Scotland will hold a second independence referendum because of the UK's decision to withdraw from the European Union. “I think an independence referendum is now highly likely, but I also think it’s important that we take time to consider all steps, and to have the discussions, not least to assess the response of the European Union to the vote that Scotland expressed yesterday," she said.

Prime Minister Alexi Tsipras of Greece said the result is a "negative development," adding that the migrant crisis was partly to blame for the Brexit vote.

Swedish prime minister Stefan Löfven said the vote result was a "wake-up call" for the EU, and that it must show it can respond to people's expectations.

Hillary Clinton, the former US secretary of state and now the presumptive Democratic presidential nominee, said the US respects the UK decision, adding that the "first task has to be to make sure that the economic uncertainty created by these events does not hurt working families here in America."

She said in a statement that theH UK’s decision raises the stakes for the November election against Donald Trump.

"This time of uncertainty only underscores the need for calm, steady, experienced leadership in the White House to protect Americans' pocketbooks and livelihoods, to support our friends and allies, to stand up to our adversaries, and to defend our interests," she said in a statement.

Trump, the presumptive Republican nominee, who arrived in the UK to visit his Scottish golf courses just as the referendum result was announced, hailed the outcome, saying voters "took back their country". "They're angry over borders, they’re angry over people coming into the country and taking over, nobody even knows who they are," he said.

He declared that the US is next. "Come November, the American people will have the chance to re-declare their independence. Americans will have a chance to vote for trade, immigration and foreign policies that put our citizens first," Trump said. "They will have the chance to reject today's rule by the global elite, and to embrace real change that delivers a government of, by and for the people."