Turkey on Wednesday strongly backed Britain staying in the European Union, a day ahead of the referendum on its membership of the bloc.
"We want Britain to stay in the European Union under any circumstances," Foreign Minister Mevlut Cavusoglu told reporters in Ankara.
London has traditionally been a strong supporter of Ankara's long-stalled bid to join the bloc. But Turkey's possible future membership has emerged as a major theme in the British referendum campaign.
Supporters of Britain's exit from the European Union have argued that the country risks being swamped by millions of Turks in the future if it remains a member and Turkey joined.
Prime Minister David Cameron countered that Turkish membership was not "remotely on the cards" and may not happen until the year 3000.
"We desire Britain to stay in the EU," said Cavusoglu. "Britain's exit would certainly have a negative impact."
But he also warned the EU would weaken if it failed to "renew itself, correct wrong policies and produce solutions to problems faced by European people... and stand strong against negative trends like racism and xenophobia".
He said EU efforts on such issues would be "only half done" if it excluded Turkey. "The EU should not be scared of a strong Turkey, and instead it should cooperate with a strong Turkey."
After applying in 1987, Turkey began EU accession talks in 2005 but its membership bid had been held up by an array of problems.
Despite repeated rows with the bloc on issues ranging from press freedom to a crackdown on Kurdish militants, President Recep Tayyip Erdogan insists that EU membership remains a strategic goal for Ankara.