Downing Street has rowed back over leaked government guidance for world leaders traveling to Queen Elizabeth’s funeral that required them to abandon their official cars and arrive by shuttle bus.

Official documents issued to overseas embassies and obtained by POLITICO Sunday stated world leaders “will be required” to leave their personal vehicles at a site in west London on September 19 and attend the funeral in shared coaches. The Foreign, Commonwealth and Development Office (FCDO) blamed “tight security and road restrictions” for the measure.

On Monday the prime minister’s official spokesman confirmed the U.K. government — rather than Buckingham Palace — is taking the lead on logistical arrangements, but refused to comment on specific details “for operational security arrangements.”

But asked if U.S. President Joe Biden would really be expected to arrive at Westminster Abbey on a bus, the spokesman said it would be left to the U.S. leader to decide.

“I think that would be a question for the U.S. and how they prefer the president to travel,” he said.

“I would say that clearly arrangements for leaders, including how they travel, will vary depending on individual circumstances. And the guidance and information provided is guidance.”

The private document sent to embassies Saturday evening was unequivocal, however. “Overseas representatives invited to attend the state funeral will be required to travel in escorted coaches via [a location in west London], where their own vehicles may wait,” it said.

The document also advised world leaders to take commercial flights to the U.K. where possible, but said private jets could be used if arriving at London’s less-busy airports.

Earlier Monday, Australian Prime Minister Anthony Albanese said he would ignore the guidance and attend the funeral in his official jet.

“I will travel this Thursday night from Australia,” Albanese told ABC Breakfast. “Those plans have been in place for a long period of time, since well before I became prime minister.”

Australian Deputy Prime Minister Richard Marles told ABC Radio National that it would not be “sensible” for a world leader like Albanese to take a commercial flight, despite the FCDO advice.

Marles, who also serves as Australia’s defense minister, said security was the “paramount consideration.”

“There are real issues of having prime ministers on commercial planes in terms of the security of the public who are also on those planes. So we’ve got to be sensible about this,” he said.

Meanwhile, the list of confirmed guests continues to grow for a diplomatic event with few parallels in recent times. Brazilian President Jair Bolsonaro, Italian President Sergio Mattarella, Irish Prime Minister Micheál Martin and South Korea’s President Yoon Suk-yeol confirmed their attendance Monday.

Leaders including U.S. President Joe Biden, European Commission President Ursula von der Leyen and New Zealand’s Prime Minister Jacinda Ardern had already done so last week.

Also likely to attend the funeral are Japan’s Emperor Naruhito, Turkey’s President Recep Tayyip Erdoğan, and French President Emmanuel Macron, among many more.

Indian Prime Minister Narendra Modi has not yet confirmed whether he will travel to London. There has been no word yet from Chinese President Xi Jinping, who will leave China this week for the first time since the COVID-19 pandemic began to attend a summit in Central Asia.