Apple's senior vice president of design Sir Jonathan Ive has dubbed some rival companies "lazy thieves" for copying his firm's products.
During an interview at the Varity Fair Summit, Sir Jony was asked how he felt about firms such as Xiaomi, which has been dubbed by some as China's Apple.
"I'll stand a little bit harsh, I don't see it as flattery. When you're doing something for the first time, you don't know it's gonna work, you spend seven or eight years working on something, and then it's copied. I think it is really straightforward. It is theft and it is lazy. I don't think it is ok at all," Ive said.
"I have to be honest, the first thing I can think, all those weekends that I could have at home with my family but didn't," he said.
Xiaomi launched its Mi 4 phone last July for around $350. The phone sold out in seconds through online retailers.
According to figures from analyst firm Canalysis, Xiaomi has 14 per cent of the smartphone market in China, while Samsung and Lenovo have 12 per cent. Apple's market share is smaller.
In July, Hugo Barra, a former Google vice president who became Xiaomi's global vice president in 2013, said he was "sick and tired" of hearing the company was copying Apple and the allegations were "sweeping sensationalist statements because they have nothing better to talk about."
Ive also talked about his time with Steve Jobs and said he learnt a valuable lesson from the late Apple chief during a confrontation with him. Ive once asked Jobs to tone down critiques of developers.
"We had been putting our heart and soul into this," he told the Apple co-founder. Jobs responded by telling Ive he was really vain. "You just want people to like you," Ive recalled Jobs telling him.
The president and co-founder of Xiaomi, Lin Bin, responded to Ive's criticisms by offering to send Ive one of the firm's smartphones.
