Sir Elton John has said he was "flattered" that President Vladimir Putin rang him to personally apologise for a hoax call.
The singer, who was in London to promote a new HIV/Aids partnership with the US government, said he was looking forward to meeting the Russian leader in person to discuss the rights of lesbian, gay, bisexual and transgender (LGBT) people in the country.
Sir Elton, who was accompanied by his husband, David Furnish, at the event in central London, took a call from President Putin at the end of September.
It followed a hoax call by two pranksters, which prompted the singer, who believed the hoax call to be from Mr Putin, to take to Instagram to say he wanted to discuss the rights of gay people in Russia.
Sir Elton said of the President's call: "I was very flattered that he reached out to me. I look forward to a further time when I can discuss things with him face to face within the next year.
"He was very gracious and he spoke good English. He apologised for the hoax call."
Sir Elton, who has two sons, also backed HIV charities in the UK in demanding that pre-exposure prophylaxis (PrEP) be made available on the NHS.
A panel is currently discussing the merits of PrEP, which substantially cuts the risk of people developing the HIV infection, and will make recommendations to the health service.
A UK clinical trial of the drug, which has the brand name Truvada, has shown it reduces the risk of infection by 86% in gay men at risk of HIV.
The drug has proved controversial over suggestions that it may lead the gay community to abandon safe sex using condoms.
Sir Elton said: "We know it works. If the treatment is there, we should take it. I'm sure crystal meth and alcohol are more dangerous in promoting unsafe sexual behaviour."
The 68-year-old also gave a speech to potential donors and officials at the US ambassador's official residence in London.
Singer Annie Lennox and actress and model Elizabeth Hurley attended the event, alongside Luiz Loures, deputy executive director of the UN Aids programme.
The project, between the Elton John Aids Foundation (Ejaf) and the US President's Emergency Plan for Aids Relief (Pepfar), will pledge 10 million US dollars (£6.5 million) in grants to organisations working to meet the needs of LGBT people. Initially, the focus will be on 10 African countries where homosexuality is illegal.
The grants will look to boost the ability of community-based organisations to deliver HIV services and work to quash the stigma of those living with HIV/Aids, or at risk of developing it.
The money will also improve screening for sexually-transmitted infections and treatment services for LGBT groups.
Sir Elton, who was wearing a dark suit, white T-shirt and trademark red glasses, said: "We need to break down the stigma for these people.
"We must help these people, it's a humanitarian issue."
Of the global fight to tackle Aids, he said: "This is one of the most important issues we face on the planet," adding: "It's a hell of a struggle we face."
He added: "As you all know, the Aids epidemic started in the LGBT community in the West.
"Gay men in the US bore the brunt of the body count and the appalling stigma and humiliation ... even in death.
"And in the face of this unspeakable horror, they organised, fought and pleaded for help, and ultimately showed the world what compassion and care really looked like.
"What a blessing it is now to see a US administration showing such extraordinary leadership in not only recognising LGBT rights at home, but reaching out to the most vulnerable LGBT communities around the world."
Sir Elton admitted he was struggling to read his speech in the dim lights of the ambassador's residence, joking: "I've got more chandeliers in my toilet."
Sir Elton is reported to be recording a new album.