With Brexit talks due to begin in just 10 days' time, a hung parliament is likely to throw a major spanner in the works.
On Friday, Michel Barnier, the EU's chief Brexit negotiator, hinted that talks could be delayed as he said they would begin only when the UK is ready. The former European Commissione suggested Brussels would be happy to postpone talks due on 19 June until the dust in Westminster has settled and a new government emerges.
Elsewhere, Council President Donald Tusk issued a stern warning that a failure to push on with no negotiations within the two-year time frame would leave Britain without a deal.
His Commission counterpart, Jean-Claude Juncker, urged Britain to form a government as soon as possible, while Belgian MEP Guy Verhoftstadt, Parliament's Brexit negotiator, called the vote an "own goal" that would make the exit process "even more complex."
German MEP Elmar Brok, a close ally of Angela Merkel, did not pull any punches in reaction to the result. He said, "Theresa May's authority in her own party is broken. She has become a weak prime minister and negotiator. It is quite possible she will go."
Former Parliament President Martin Schulz, who is standing against Angela Merkel in the upcoming German elections, said he spoke to Labour leader Jeremy Corbyn on the phone and would meet with him soon.
Jarosław Gowin, deputy prime minister in Poland's conservative government, described the result as a "bad sign for Europe", explaining that it "deepened the uncertainties over the future of Europe."
As the results of the British election sent shockwaves around the world - and the reality of a hung parliament threw Brexit negotiations into doubt - Theresa May's future as prime minister and leader of the Conservatives was being openly questioned on Friday after her decision to hold the snap election disastrously backfired.
May had pledged to offer "stability" if the Tories end up as the largest party with the most votes. But, speaking as the results rolled in on Thursday, Conservative former minister Anna Soubry said she should "consider her position" and take personal responsibility for a "dreadful" campaign and a "deeply flawed" manifesto.
Within moments of a shock exit poll suggesting no party would achieve an overall majority, Sweden's former foreign minister Carl Bildt described the poor result for the Conservatives as the "price to be paid for the lack of true leadership".
Bildt, who is now the co-chair of the Brussels-based think tank, the European Council on Foreign Relations, said on Twitter that the outcome looked "messy".
The snap election was particularly bad for Ukip and its leader, Paul Nuttall, who failed in his bid to be elected MP for Boston and Skegness, resigned as leader on Friday morning.
He said he believed he had laid the foundations for future Ukip success but added, "It will be for someone else to build on those. It has been an honour to lead the party I love."