Plans being considered by Michael Gove suggest the government is planning a two-pronged attack on the Freedom of Information Act (FoI) following the publication of Prince Charles' 'black spider' letters.

The new justice secretary is understood to be trying to include officials' 'thinking time' in the costs of FoI requests, thereby making it harder to request information without falling foul of a £600 limit on costs.

The news comes as David Cameron said he would look into ways of tightening up the ministerial veto over FoI request, in the wake of his lost battle to prevent the publication of Prince Charles' letters to members of the government.

The letters, which detailed the prince's views on a range of issues, were published following a protracted legal battle, with then-attorney general Dominic Grieve's being told he was wrong to try and use his ministerial veto by the supreme court.

How Whitehall neutered the Freedom of Information Act

In the wake of the publication, the prime minister said:

"Our FoI laws specifically include the option of a governmental veto, which we exercised in this case for a reason. If the legislation does not make parliament’s intentions for the veto clear enough, then we will need to make it clearer."

While the government investigates how to tighten up rules around the ministerial veto, Gove appears to be investigating other options for restricting the public's right to FoI.

The Financial Times, which recently discovered a three-month automatic deletion programme for Downing Street emails in a bid to avoid the legislation, reported that Gove was currently considering how to implement 'thinking time' changes to FoI.

Under current rules, there is a £600 cost limit for government departments and £450 for other public bodies. The government may choose to lower that limit or insert additional costs into it – such as official's 'thinking time' – making it harder to satisfy.

A 2012 report by the justice select committee found a 'thinking time' addition to the rules "does not seem to us to be a feasible proposition".

They added:

"Such activities are overly dependent on the individual FoI officer's abilities, introducing an element of inconsistency into the process that undermines the fundamental objective of the Act, that everyone has an equal right to access information."

Even under the current rules, campaigners and journalists are regularly told that the information they seek is not centrally held and that providing an answer would therefore be "disproportionately expensive".

Officials often do not collect information which may prove embarrassing to the department, while others do not hold it centrally, so that requests can fall under an S12 'cost of compliance' exemption.

Other requests are met with an S22 exception saying the information is intended for future publication, although officials often refuse to confirm when the future publication will take place.

Another useful exception for officials is S35, which exempts documents involved in the formulation of government policy. Although the exception is intended for high-level policy, campaigners suspect it is used far more broadly.

There is also an S36 exception for prejudice to the 'effective conduct of public affairs' and an S43 exception on the commercial interests of private firms running public services, like G4S or Serco.

High-level outrage at the FoI Act is not a new development. Even Tony Blair, who oversaw the introduction of the Act, came to regret it. In his memoirs, he wrote about his feelings towards himself after passing it: