British Prime Minister Theresa May and opposition leader Jeremy Corbyn remained silent on the defections from both parties.
British Prime Minister Theresa May faced weekly questions from lawmakers in the House of Commons as three Conservative MPs defect to the newly formed Independent Group.
Watch today's PMQs in the above video player.
May said she will seek "legally binding changes" to the Withdrawal Agreement when she travels to Brussels later on Wednesday.
British lawmakers rejected May's Brexit deal last month, criticising the backstop arrangement which plans for Northern Ireland to remain in the EU's customs union should both parties fail to find an alternative arrangement before the end of a planned transition period.
The prime minister said she will allow Parliament to vote on her Brexit deal as soon as possible.
"We have listened to the House of Commons, we are working on the views of the House of Commons with the European Union, and we will bring a vote back when it is the right time to do so," May said.
Opposition leader Jeremy Corbyn described her strategy as "quite confusing" and called on her to rule out a no-deal Brexit.
May retorted by asking Corbyn to "tell us what his policy is — to back a deal or to stay in the European Union?"
She also rejected Honda's decision to close a plant in Swindon as Brexit related.
"The decision this week by Honda is one that is deeply disappointing. They have made absolutely clear this is not a Brexit-related decision. This is a decision about the change that is taking to the global car market,"she said.
Asked about anti-semitism, the prime minister said: "I never thought I would see the day when Jewish people in this country would be worried about their safety in their country" or that the "once proud Labour party" would be accused of anti-semitism.
"It is racism and we should act on it," she added.
Labour Party Leader Jeremy Corbyn said his own party "takes the strongest action to deal with anti-semitism whenever it rears its head."
"Anti-semitism has no place whatsoever in our society or any of our political parties," he added.
It comes after eight Labour Party MPs quit earlier this week denouncing the party's Brexit strategy and accusing Corbyn of allowing "the Labour Party to become institutionally anti-semitic."
May said it is important for "this government and this country to take action against those who are involved in terrorism."
It comes a day after the UK moved to strip Shamima Begum of her citizenship after she travelled to Syria to join the so-called Islamic State (IS). The 19-year-old, who gave birth last week to a son she had with a jihadist fighter, is currently in a detention camp in Syria.
May added that British citizens coming back to the UK after joining the ranks of IS should be in "no doubt" that they "will be questioned, investigated and potentially prosecuted."
Noticeably, no word was uttered by either May or Corbyn on the 11 MPs — eight former Labour MPs and three MPs from the ruling Conservative Party — who left their respective parties' ranks to form a newly-created Independent group.
Nicola Sturgeon, leader of Scotland's National Party, criticised the omission on Twitter.
"Striking how symbiotic the May/Corbyn relationship seems — collusion of silence on their imploding parties, neither showing any leadership on Brexit and each one relying on the other's incompetence to obscure their own," she said.
The 11 MPs sat together on the backbenches. Their group is now as large as the Liberal Democrats and bigger than Northern Ireland's Democratic Unionist Party whose 10 MPs prop up May's minority government.