Immigration Minister Mark Harper had "no choice" but to resign, Ukip leader Nigel Farage said, after discovering that Mr Harper's cleaner was in the UK illegally.
Mr Farage said: "After all he was the guy behind what I thought were those rather unpleasant vans driving around London saying 'if you're an illegal the time has come to go home', so he had no choice,"
"It rather sums up the very bad few weeks the Government has had with the question of immigration and what a mess the whole thing is."
The Labour party has said that the resignation of Immigration Minister Mark Harper demonstrates the complexity of immigration checks for landlords and employers.
Mr Harper resigned after discovering that his cleaner was in Britain illegally, although Downing Street said there was nothing to suggest that he knowingly employed an illegal immigrant.
"This information about Mark Harper’s employee does put him in a difficult position," Mr Hanson said.
"Perhaps once again the government need to think very carefully about how they approach this issue, as it is clear there are limits to the effectiveness of relying on employer and landlord checks to address illegal immigration."
Mark Harper, who has resigned as Immigration Minister after discovering that his cleaner was in the UK illegally, said that he felt compelled to resign even though he had "complied with the law at all times".
In his resignation letter to Prime Minister David Cameron, the Conservative MP said: "As Immigration Minister, who is taking legislation through Parliament which will toughen up our immigration laws, I should hold myself to a higher standard than expected of others."
He added: "I have always believed that politics is a team game, not an individual sport.
"Under the circumstances, I have therefore decided that the right course is for me to return to the backbenches. I am sorry for any embarrassment caused."
Mr Harper said he would continue to support the Conservative party and the government "in whatever way I can".
"Mark Harper offered his resignation after he was informed that his cleaner did not have indefinite leave to remain in the United Kingdom, despite having shown him documents claiming she did," a Downing Street statement read.
"He immediately notified the Prime Minister - who accepted his resignation with regret. There is no suggestion that Mr Harper knowingly employed an illegal immigrant."