DUBAI, United Arab Emirates — Dubai has enacted strict new measures to curb the spread of Covid-19 and is defending its pandemic response strategy after a surge in cases. 

Record breaking infection rates in recent weeks have forced Dubai to introduce new venue capacity cuts and a night curfew, after opening itself to tourists. Authorities blamed "a marked increase in the number of violations of precautionary measures" for the new rules.

In the last week, the U.K. has suspended all UAE flights — the world's busiest international route. Meanwhile, Dubai on Wednesday banned its popular brunches, closing pubs and bars. 

"The approach in the UAE and in Dubai in particular has always been underpinned by science, and science informed common sense," Alawi Alsheikh-Ali, deputy director of the Dubai Health Authority told CNBC's Hadley Gamble on Thursday.  

"The numbers have surged but the health system has managed to keep up with the numbers and take care of the sick, and there has been more restrictions now in terms of activities in the Emirate and the UAE in response to that," he added.

But as images of busy beaches and Instagram celebrities on social media spark anger and envy in the international press, some are questioning the wisdom of Dubai's strategy.

"What has happened in Dubai did not need to happen," Erin Bromage, a professor of biology at the University of Massachusetts Dartmouth, who specializes in infection and immunology, told CNBC.

"They have brought the virus in, including the new variants, in waves of new tourists and allowed it to spread through the community as well as spread to uninfected tourists," Bromage said. "The tourists return home and seeded infections there, possibly with the new variants."

Figures from the U.K. Civil Aviation Authority show almost 300,000 people traveled between the U.K. and UAE during November and December last year alone, with thousands flocking to Dubai's hotspots for an escape from lockdowns. 

In the critical month of December — when a new and highly transmissible variant of the virus was spreading in the U.K. — 211,115 people traveled between the U.K. and the UAE. The data only shows traffic to and from the U.K. and not other countries, meaning the total number of travelers is likely much higher. Testing was required for passengers before boarding or on arrival. 

"We've been following the numbers very carefully, and we're very concerned by the rise in numbers and the emergence of new variants about two months ago," Alsheikh-Ali said.

Cases have tripled since November, but UAE authorities deny the community has been put at risk and reject the idea that the city has become a hotspot for spreading the virus abroad. 

"We've seen variants … reported now in more than 70 different countries," Alsheikh-Ali said. "I don't think it's helpful to identify a particular country as a particular source for a certain variant," he added. 

Dubai's business community, who benefited from the open door policy, is also pushing back.

"The infection rates are much higher in the U.K. than they currently are in the UAE, so making the case that somehow the UAE is causing issues or is a superspreader country is clearly not the case," Chris Payne, chief economist of Dubai-based Peninsula Real Estate, told CNBC.

"The UAE have taken a different track, Dubai specifically, and I don't blame them for that," Payne added. "They've taken the view that the economy of Dubai needed to open, and it couldn't withstand the kind of prolonged closures that we've seen elsewhere in the world."

The were 3,310 new coronavirus cases recorded in the UAE on Wednesday, up from 2,730 on Tuesday, according to official data from Johns Hopkins University. The UAE seven day-average case count stands at 3,500.  

As debate rages over Dubai's virus strategy, at least two countries have raised concern about passenger flows in recent weeks.

Danish Transport Minister Benny Engelbrecht said at least "one citizen" brought the South African variant of the virus "back from Dubai." Denmark has temporarily banned flights from the UAE amid criticism over Emirati testing facilities.

The UAE has one of the highest per capita testing rates in the world, with the total number of tests exceeding 26 million to date. Authorities said testing centers operate by international standards and are inspected regularly. 

Concern has also come from Israel, where more than 900 travelers returning from Dubai have been infected with coronavirus, according to a report in the Associated Press citing the Israeli military. It said returnees "created a chain of infections numbering more than 4,000 people." 

CNBC was not able to independently verify the report and has contacted the Israeli military for comment.  

Despite the claims, UAE authorities insist they are taking effective action to protect the safety of those living in and visiting the UAE. That also includes frontline health care workers dealing with the rising cases. 

"It's not a good idea, but life must go on," one medical worker who was conducting PCR tests in the financial area told CNBC when asked if Dubai should stay open to travelers. "We just need to be responsible and take care. I've taken my vaccine," the worker, who preferred to remain anonymous as they were not confident speaking publicly without employer authorization, said. 

Authorities also dismissed suggestions of a shortage of hospital beds in Dubai.  

"The health system here in Dubai has been able to stay ahead of the curve with surge capacity. Every patient who needs a hospital bed is able to get it today in Dubai," Alsheikh-Ali said. 

The UAE is at the forefront of a global vaccination drive. Using the Chinese Sinopharm and BioNTech-Pfizer jabs, it has already delivered more than 2.7 million doses and is on target to immunize half of its 10 million residents during the first quarter.

"We currently have three different vaccines available for people in Dubai, with more than 120 access points for vaccines including home vaccinations for the elderly who cannot make it to the vaccination centers," Alsheikh-Ali said, when asked how authorities planned to ease the most recent round of restrictions.

"Vaccinations are our exit strategy."