Jeremy Corbyn has accused Theresa May and her ministers of issuing "contradictory messages" on Brexit which are exacerbating the "huge uncertainty" about the UK's future.
The Labour leader's attack on the Prime Minister comes amid growing concerns that ministers are struggling to agree on a strategy for divorce negotiations with Brussels.
But Mrs May appeared to take aim at critics who have suggested that the Government position is unclear by telling MPs she will not reveal her hand on negotiations "prematurely".
Earlier this week the Prime Minister distanced herself from Brexit Secretary David Davis's suggestion that it is "very improbable" the UK can regain control over its own borders while remaining part of the European single market.
Mrs May's spokeswoman said Mr Davis was expressing a personal opinion on the single market rather than official policy.
But Mr Corbyn said the apparent differences in opinion are making worse the "huge uncertainty about what comes next" for the UK.
He also bemoaned an "extraordinary lack of planning and preparation" from the Government on how to navigate Brexit as he responded to a Commons statement on last weekend's G20 summit from Mrs May.
"That uncertainty and division has been made worse by the Government's ministers' political posturing and often very contradictory messages which doesn't seem to add up to a considered position," he said.
He suggested that Mr Davis's position and that of the PM are incompatible.
"It's one or the other," he said.
"It can't be both. So can the Prime Minister tell the House what the Government's policy actually is?"
Meanwhile, Mrs May told the House that she did not intend to provide a "running commentary" on the Government's progress towards delivering Brexit.
She said: "Our task now is to deliver the will of the British people and negotiate the best possible deal for our country.
"I know many people are keen to see rapid progress and to understand what post-Brexit Britain will look like.
"We are getting on with that vital work but we must also think through the issues in a sober and considered way.
"As I've said, this is about getting the kind of deal that is ambitious and bold for Britain.
"It's not about the Norway model or the Swiss model or any other country's model - it's about developing our own British model.
"We will not take decisions until we are ready, we will not reveal our hand prematurely and we will not provide a running commentary on every twist and turn of the negotiations."
But Mr Corbyn hit back and said: "The Prime Minister said she wasn't going to reveal her hand on this subject.
"Nobody would blame her because she hasn't revealed her hand or indeed any of the Government's many hands.
"On this particular thing they are unclear of what they are trying to do."
Mrs May's trip to the G20 summit was largely dominated by issues relating to Brexit with a particular focus on trade and the way in which the UK will position itself globally after it has left the EU.
Australian PM Malcolm Turnbull promised to strike an "early ... very strong, very open free trade agreement" with the UK but Japan warned of the possibility of its companies leaving a post-Brexit Britain while Barack Obama confirmed the US will seek trade deals with the EU and Pacific states before the UK.
Mrs May also used her trip to China to rule out the introduction of an Australian-style points-based immigration system as proposed by Leave campaigners.
The Prime Minister told MPs "forging new relationships" will be key to making Brexit a success.
She said: "When the British people voted to leave the European Union, they did not vote to leave Europe, to turn inwards or to walk away from the G20 or any of our international partners around the world.
"That has never been the British way. We have always understood that our success as a sovereign nation is inextricably bound up in our trade and our co-operation with others.
"By building on existing partnerships, forging new relationships and shaping an ambitious global role, we will make a success of Brexit - for Britain and for all our partners - and we will continue to strengthen the prosperity and security of all our citizens for generations to come."