Theresa May has insisted the UK is making the running in Brexit negotiations amid fresh criticism from Brussels.
The Prime Minister said her Government had been "coming forward with the ideas", but key Brussels players including Michel Barnier and Guy Verhofstadt continued to express frustration about the UK's approach.
The European Union's chief Brexit negotiator Mr Barnier said the guidelines set by Brussels were designed for "serious and constructive negotiations" but there needed to be "clear UK positions on all issues".
Mr Verhofstadt, the senior MEP leading Brexit work for the European Parliament, said there was "slow progress" in the talks and suggested it would be "very difficult" to move onto discussing the future trade relationships unless there were breakthroughs in the negotiations.
Brexit Secretary David Davis is due to return to Brussels on Thursday at the end of the latest round of talks with Mr Barnier's task force.
Updating MEPs on the latest developments, Mr Verhofstadt said: "We need from both sides position papers on every issue before you can really start a negotiation. If only one party around the table is putting in a position paper and the other party is not responding then it is very difficult to start a negotiation."
Mr Verhofstadt played down UK hopes that talks on trade could begin after an assessment in October of whether sufficient progress had been made on citizens' rights, withdrawal arrangements and the financial settlement.
"If it goes very slow, as it is the case for the moment, it will be very difficult to say that there is sufficient progress when we are in October," he said.
Speaking in Japan at the start of a mission aimed at forging post-Brexit trade links, Mrs May defended the work done by the UK.
She told the BBC: "We have been publishing a series of papers over the summer, there will be more papers to come, where we are setting out the key issues that both sides need to address, the options that we have, the ideas we have, of how to deal with those.
"It's the United Kingdom that has been coming forward with the ideas and with the clarity about the future."
And she said she was still prepared to walk away from talks without a deal.
Asked if she still believed no deal is better than a bad deal, she said: "Yes, I think that is right. But if you talk about the point at which we leave the European Union, we want to ensure that at that point we do have a deal and that we have a deal that is the right deal for the UK."
But Mr Verhofstadt claimed that a "no deal scenario" was "not an option anymore".
"At a certain moment, everybody was talking about - also in Britain - 'no deal is better than a bad deal'. All this is no longer in the air for the moment."
Former Tory leader Lord Hague told BBC 5 Live that the election result "weakened the British government's negotiating position" and Brexit may now be "softer than it might have been".
"So Britain will get a worse deal as a result of the election. I think there is no question about that.
"And of course we can't blame the voters for how they vote. The voters have voted to leave the EU, and then not to have a government in a strong position to negotiate the exit."