The coronavirus-delayed Expo 2020 has opened in Dubai, with organisers aiming to stage the largest global gathering since the start of the pandemic.

More than 190 countries are showcasing their cultures and innovations inside architecturally striking pavilions on the 438-hectare (1,083-acre) site.

Dubai's government has spent an estimated $7bn (£5.2bn) on the event.

It hopes to attract 25 million visitors over the next six months to boost tourism and investment in the emirate.

Organisers say they have been "delighted" with ticket sales, but analysts believe they will struggle to meet the target because of the continuing restrictions on global travel.

Citizens of all countries can visit the United Arab Emirates if they are fully vaccinated with one of the World Health Organization-approved Covid-19 vaccines.

To get into the Expo itself, all those aged 18 and over will be required to show proof of a vaccination or a negative PCR test. Free testing will be available to ticket-holders on site.

Dubai's ruler has promised an "exceptional event to be engraved in mankind's memory"

Dubai's ruler, Sheikh Mohammed bin Rashid Al Maktoum, declared the Expo open at a ceremony on Thursday evening that featured stars from across the world, including Italian tenor Andrea Bocelli, British popstar Ellie Goulding and Chinese pianist Lang Lang.

Sheikh Mohammed told the Al Bayan newspaper this week that it would be "exceptional event to be engraved in mankind's memory".

"We take pride in welcoming representatives of 192 countries to the land of tolerance, as we invest in this global gathering to find solutions to global challenges on the grounds of international co-operation that humanity is in need of," he said.

China's pavilion is one of the largest at the Expo and is shaped like a traditional lantern; Morocco's was made with traditional mud-building methods; and Saudi Arabia's includes the world's largest interactive lighting floor, LED mirror screen and interactive water feature.

The site is located in the southern suburbs of Dubai and is bigger than 600 football fields

The UK's pavilion is inspired by a project from the late scientist Stephen Hawking and features a 21m-tall (69ft) structure made of slats on which algorithmically generated words appear to form a "Breakthrough Message".

There has been some criticism of the event because of the UAE's human rights record.

Earlier this month, the European Parliament urged member states not to participate in the Expo and companies to withdraw their sponsorship.

A resolution cited what it described as the "systematic persecution of human rights defenders, journalists, lawyers and teachers speaking up on political and human rights issues in the UAE", as well the country's "inhumane practices against foreign workers" who constitute 80% of the population.

The UAE foreign ministry rejected the resolution, saying the allegations it contained were "factually incorrect". It also insisted that the country's laws provided for the fair treatment of all citizens and residents.