* Royal Mail share price up sharply since sale last Oct
* Opposition, unions accuse government of botching sale
* Two parliamentary committees to quiz bankers, ministers
LONDON, April 25 (Reuters) - British government ministers and bankers responsible for the sale of Royal Mail will face another round of questioning by lawmakers next week over whether the state postal operator was sold off too cheaply.
Last October, the government sold 60 percent of Royal Mail at 330 pence per share, ending 500 years of state control and raising 2 billion pounds ($3.36 billion) for the public purse.
However, the firm's share price has since risen by as much as 87 percent, offering quick profits for big banks and City investors and drawing heavy criticism from trade unions and the opposition Labour Party who say the government botched the deal.
That view was reinforced this month by a National Audit Office (NAO) report which said taxpayers had been short-changed by at least 750 million pounds.
On Tuesday, British Business Secretary Vince Cable will face lawmakers for a third time to defend the sale price, appearing before the Business, Innovation and Skills Committee alongside fellow minister Michael Fallon.
Separately, parliament's Public Accounts Committee will quiz Martin Wheatley, chief executive of the Financial Conduct Authority, and his senior official William Amos on Monday on how the sale was handled. It will question the bankers on Wednesday.
William Rucker, chief executive of Lazard, which advised Britain on the float, will be grilled on its role, alongside James Robertson and Richard Cormack of UBS and Goldman Sachs, the two banks that led the sale.
It will be their second time to appear before lawmakers.
Also facing questions on Wednesday will be Martin Donnelly, Permanent Secretary for the Department for Business, Innovation and Skills, and management from Shareholder Executive, which looks after government stakes in businesses.
While committees do not have statutory powers to enforce their conclusions, they are often influential in shaping future work and their critical focus on the Royal Mail sale has already proved an embarrassment to the government.
In its April 1 report, the NAO criticised the government's dependence on advisers during the process and questioned the incentive given to Lazard, which was to secure a sale and was not dependent on the value achieved.
The amount raised in the sell-off, which followed three failed attempts to privatise Royal Mail in 20 years, has been defended by ministers and bankers, who have said long-term investors would have walked away if the offer price had been raised at a time when the firm faced the threat of strike action.
Both have also dismissed pre-sale pitches from several banks that valued Royal Mail's equity at as much as 8.5 billion pounds, well above its eventual 3.3 billion float valuation. The ministers and bankers say the pitches were flawed due to a lack of detailed information.
Royal Mail's shares traded at 525 pence early on Friday, still 59 percent above its offer price, valuing the business at around 5.3 billion pounds.
($1 = 0.5960 British Pounds) (Editing by Gareth Jones)