Image copyright Getty Images Image caption The Duke of Sussex flew commercially to the event in Amsterdam

The Duke of Sussex has defended his use of private jets, saying he occasionally needs to ensure his family is safe.

Speaking at the launch of an eco-tourism project in Amsterdam, Prince Harry added that he balances out the impact this has on the environment.

The duke and his wife Meghan have faced criticism after newspapers claimed they flew privately four times in 11 days this summer.

Prince Harry said he flew to the event on Tuesday commercially.

At the launch of Travalyst, aimed at encouraging the tourism industry to become more sustainable, the duke was asked about his travel behaviour.

"I came here by commercial. I spend 99% of my life travelling the world by commercial," he said.

"Occasionally there needs to be an opportunity based on a unique circumstance to ensure that my family are safe - it's generally as simple as that."

During his opening speech, the duke said "no one is perfect" in terms of his impact on the environment.

Questions have been asked about the royal couple's use of private jets and their impact following their support of environmental causes.

Prince Harry has previously spoken about the importance of tackling climate change.

In September's edition of Vogue - edited by Meghan - the prince spoke about environmental issues and his love for nature, saying: "We are the one species on this planet that seems to think that this place belongs to us, and only us."

The Sussexes came under fire over the summer after taking a private flight to the home of singer Sir Elton John, in Nice.

Sir Elton defended the royal couple, saying he provided them with his private plane to "maintain a high level of much-needed protection".

He also said he paid to carbon offset their trip to his French home.

Image copyright Press Association Image caption Sir Elton John performed at Harry and Meghan's wedding

Carbon offsetting allows passengers to pay extra to help compensate for the carbon emissions produced from their flights.

The money is then invested in environmental projects - such as planting trees or installing solar panels - which reduce carbon dioxide in the air by the same amount.

The duke said that what is important is "what we do to balance out" negative effects.

He went on to say that he has always offset his carbon emissions and will continue to do so.

"In my mind it's the right thing to do and we need to make it cool," he said.

"We have to connect people to where that little bit of extra money is actually going."

Prince Harry has spent three years working on the project alongside five co-founders - Booking.com, Ctrip, Skyscanner, TripAdvisor and Visa.

He hopes it will improve conservation, environmental protection and help increase the economic benefits of tourism for local communities.

Figures from accounts published in June show the royal household's carbon emissions due to business travel almost doubled last year.

The increase was put down to the use of chartered flights for more overseas visits, which are planned by the Foreign Office.

However, emissions savings from greener heating and lighting meant the household's overall carbon footprint stayed around the same as the previous year.