The UK government is to push for capped fee arrangements with its external legal advisers following controversy over Freshfields Bruckhaus Deringer's £2.8m bill for its work on the sale of Eurostar last year.

The government completed the sale of its 40% stake in Eurostar for £757m in March 2015, but later in the year the National Audit Office (NAO) found the sale had left the taxpayer up to £2.3bn out of pocket and criticised the £2.8m of legal fees paid to Freshfields.

A subsequent report by the Public Accounts Committee (PAC) called for the government to introduce capped fee arrangements with law firms and, last month, the government accepted this recommendation.

It said it: "will seek capped fees although this will be dependent on the detail of the individual project and the negotiated commercial contract between the government and advisory firms."

However, it defended its instruction of Freshfields and stated that the legal fees paid to the firm "were fully justified".

It added that "advisers were only used where external advice was required because the specific commercial expertise was not available in government or resources were not available".

At a Public Accounts Committee (PAC) meeting in November Conservative MP Stephen Phillips QC pushed senior Whitehall officials to justify the cost of instructing Freshfields on the Eurostar deal.

Mark Russell, chief executive of the Shareholder Executive – which oversees the management of state-owned assets – told the Committee: "We in government are paying too much to advisers but I don't think it is just in public finance, I think it is across the piece."

Phillips expressed concern that Freshfields partners charged "Rolls Royce" level fees for their advice, while Conservative MP David Mowat criticised the close relationship the government has with magic circle firms. "Taxpayers feel that the relationship with law firms gets too cosy," he said.

Meanwhile Labour MP, and chair of the PAC committee, Meg Hillier warned that future committees would investigate how much law firms charge for their advice to the government.

Speaking to Legal Week she said: "We'd all been shocked at the Freshfields figure, and it was something we want to probe."

She added that the responsibility for negotiating "reasonable charges" lay both with the government and law firms and that the government "should not be signing a blank cheque" to law firms.