Former Foreign and Commonwealth Office permanent secretary Sir Simon Fraser, photographed for CSW by Jack Lawson
The UK has been "absent" from the opening round of Brexit talks because the government has "no clear position" on negotiations, according to the former top civil servant at the Foreign Office.
Sir Simon Fraser, who served as permanent secretary at the FCO until 2015, said rows between ministers over a variety of issues had hindered progress.
Cabinet ministers have been in open conflict about areas such as post-Brexit migration and the length of any transitional agreement with Brussels, with chancellor Philip Hammond the subject of repeated negative briefing from colleagues.
After two rounds of talks between Brexit secretary David Davis and the EU's chief negotiator Michel Barnier, there are still substantial differences on the issues of citizens' rights, the jurisdiction of the European Court of Justice and the size of the UK's so-called "divorce bill".
Reports over the weekend suggested the government could be prepared to pay £36bn to settle its financial commitments to the EU – although Downing Street has played down the claim.
Sir Simon said the UK needed to set out its stall more clearly on such areas, as well as on the future border between Northern Ireland and the Irish Republic.
"The negotiations have only just begun, I don't think they have begun particularly promisingly, frankly, on the British side," he told BBC Radio 4's Westminster Hour last night.
"We haven't put forward a lot because, as we know, there are differences within the Cabinet about the sort of Brexit that we are heading for.
"Until those differences are further resolved I think it's very difficult for us to have a clear position."
He added: "I think so far we haven't put much on the table apart from something on the status of nationals, so we are a bit absent from the formal negotiation."
A spokesman for the Department for Exiting the EU played down the suggestion that negotiations were not progressing well.
He said: "Government officials are working at pace and we are confident we will have made sufficient progress by October to advance the talks to the next phase."