“I have decided to leave Ukip because it has become a vanity project for Nigel Farage … He runs the party like a dictator, employs people who are totally inappropriate for party positions and gets rid of anybody who stands in his way,” Bashir said in the letter published in the Daily Mail.
Bashir added that he was racially abused by UKIP members on social media.
Bashir joined UKIP for its support of the United Kingdom's independence from the EU. However, Bashir said that he trusted the Conservative party led by Prime Minister David Cameron will deliver on an EU referendum.
Cameron pledged to hold a referendum by 2017 on whether the United Kingdom should stay in the EU, if his party wins the upcoming general elections in May.
Meanwhile, UKIP posted a statement on Saturday claiming Bashir was suspended from the party pending investigations on "unanswered financial and employment questions."
Bashir is a Pakistani-born businessman and served as an UKIP Member of the European Parliament for less than a year.