SINGAPORE — Qatar Airways CEO Akbar Al Baker is no stranger to controversy. The outspoken airline boss, known for his sometimes colourful attacks on his rivals, has now apparently taken issue with Singapore's Jewel Changi Airport.

Jewel, said Mr Al Baker, allegedly copied the design for Qatar's Hamad International Airport's expansion, reported The Straits Times on Monday (Nov 4).

During an unveiling of the expansion plans in Doha two weeks ago, Mr Al Baker was quoted as saying: "When I show you the images later (of the planned enhancements), you will realise that somebody copied our design, which was already on the table nearly six years ago... We had individuals from that country, I will not name it, that took our design and did it."

Mr Al Baker's reference was immediately obvious — the expansion plans feature an indoor waterfall and large gardens similar to Changi's Jewel.

Changi Airport Group's chief executive Lee Seow Hiang, however, has rebutted the allegation, telling The Straits Times: "We value the originality and creativity of ideas as we innovate to elevate the Changi experience for all our visitors. We respect intellectual property rights and expect the same of all our partners."

TODAY takes a look at some of Mr Al Baker's other comments which have left observers scratching their heads.

1. In July 2017, Mr Al Baker said that American airlines were “crap” and their passengers were "always being served by grandmothers", in a speech at a gala dinner to celebrate the launch of a Dublin-Doha route in Ireland. According to a BBC report, he also boasted that the average age of his cabin crew was “only 26". He later apologised for his remarks and said that they were "careless" and did not reflect his "true sentiments about cabin crew".

2. At a widely-reported press conference in June last year following his election as chairman of the International Air Transport Association, Mr Al Baker caused a furore when asked about gender diversity among Middle Eastern airlines, and whether his job could be done by a woman. He reportedly answered: “Of course it has to be led by a man, because it is a very challenging position.” He later apologised, saying that he was attempting to make a joke.

3. It is no secret that Mr Al Baker and Delta Air Lines CEO Richard Anderson loathe each other. In fact, Mr Al Baker has even called the latter unethical, unpatriotic and weak. According to media agency Mashable in December 2015, Mr Al Baker said that Mr Anderson’s criticisms of Gulf carriers as "governments" were "nonsense”, with the goal of stifling the competition "so he can swindle American passengers even more”. The agency also reported that Mr Al Baker said of Mr Anderson: "Let him come face to face with me in any forum... I will hang him on a wall.”

4. Airline news agency One Mile at a Time reported that when United States President Donald Trump was facing backlash after his remarks suggesting the possibility of banning Muslims from the US, Mr Al Baker was quick to defend him, saying that Mr Trump was his long-time friend. “I think it is an exercise only to gain political mileage. Nothing more. This is the opportune time to excite more extremist people so that they could give him their votes,” he said, according to the report.

5. In May 2016, The Daily Telegraph reported that Mr Al Baker said backpackers were not welcome in Qatar because they “just lie on the beach and don’t spend money” and the country wanted to “attract people of higher standard”. He went on to explain that, unlike neighbouring Dubai, Qatar did not want backpackers as it would give the country a bad look.