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."
Immigration Minister Mark Harper's resignation over his employment of a cleaner in UK illegally is refreshing, a Tory MP has said.
John Penrose, MP for Weston-super-Mare told Murnaghan on Sky News that Mr Harper had stood down on a point of principle. He added:
Communities Secretary Eric Pickles said he was "very sorry" to hear about the resignation of Immigration Minister Mark Harper.
Mr Harper resigned after discovering the cleaner he employed was in the UK illegally.
"I'm very sorry to hear about Mark Harper. He was a very good administer. I've known him a long time but I recognise the Prime Minister has accepted the resignation," Mr Pickles told ITV News.
"My best wishes go to him and his family."
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."
Junior Home Office minister James Brokenshire has replaced Mark Harper as Immigration Minister, who resigned after discovering that his cleaner was in Britain illegally.
Karen Bradley will move from the whips office to fill Mr Brokenshire's role.
Ms Bradley will be succeeded by John Penrose within the whips office, and Harriet Baldwin will be brought into the government as a junior whip.
Conservative MPs have voiced their support for Mark Harper, who has resigned as Immigration Minister after he discovered he was employing a cleaner who no longer had the right to live in the UK.
Tory MP Nick de Bois said he was "very sorry" to hear of Mr Harper's departure, calling him "a very good minister, colleague and decent man".
Conservative MP Andrew Percy said Mr Harper was a "really decent guy", and said it was "like him to act honourably" by resigning as he did.
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".
Following the resignation of Immigration Minister Mark Harper, Home Secretary Theresa May said:
The Prime Minister accepted the resignation of Immigration Minister Mark Harper "with regret", Downing Street said.
Harper announced his resignation over his employment of a cleaner who was not permitted to work in the UK.
"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."
There is "no suggestion that Mark Harper knowingly employed an illegal immigrant", Downing Street have said.
The Immigration Minister has announced his resigned over the issue.
Number 10 said David Cameron had "accepted his resignation with regret".