LONDON (Reuters) - Britain has not blocked the export of COVID-19 vaccines, a UK government spokesman said on Tuesday. “The UK government has not blocked the export of a single COVID-19 vaccine. Any references to a UK export ban or any restrictions on vaccines are completely false,” the spokesman said. “This pandemic is a global challenge and international collaboration on vaccine development continues to be an integral part of our response.” Earlier European Council President Charles Michel rejected charges of “vaccine nationalism” levelled against the EU, and said that while Britain and the United States have outright bans on exports of COVID-19 shots, the EU had not stopped exporting.