Republican presidential aspirant and business tycoon Donald Trump has lashed back at reigning Miss Universe Paulina Vega, who earlier described his comments against Mexican immigrants as "unjust and hurtful."

On his official Twitter page, Trump called the beauty queen a "hypocrite" for criticising him, yet choosing to hold on to her crown as Miss Universe.

In response, Vega described the presidential aspirant as "comical."

"I think what I'm doing is the least hypocrite thing I can do by using my voice clearly," the beauty queen said.

"I have a legally binding contract and legal relationship with the organisation, and it's not so easy for me, like the artists have done, to renounce and say, 'No. I'm not working for you anymore.' I have a contract of one year," she added.

Vega added that she will "keep going forward and refuse" to let Trump's comments affect her.

"Miss Universe, the organisation, and I are much more than what that man says on Twitter," the reigning Miss Universe said of Trump's tirades.

"Miss Universe, Paulina Vega, criticised me for telling the truth about illegal immigration, but then said she would keep the crown. Hypocrite," Trump, who partially owns the Miss Universe Organization, said.

The controversial mogul and "The Apprentice" star was reacting to Vega's recent Instagram post calling out Trump for accusing Mexican immigrants of "bringing drugs" and "bringing crime" to the United States.

"As a Colombian and as Miss Universe, I want to show my support and validate the sentiments of the Latin community," the reigning Miss Universe, who hails from Colombia, said on her Instagram account.

Trump's recent remarks also prompted NBC, which traditionally airs the Miss Universe pageant every year, to announce that it will no longer do so this year after the businessman's tirades.

Mexico has also chosen not to send a candidate to the annual beauty pageant due to Trump's statements.