The Labour party has called on David Cameron to release all details of his involvement in the Greensill lobbying scandal. Sir Laurie Magnus, Rishi Sunak’s adviser on ministerial interests, has also been asked to explain whether investigations into the foreign secretary’s former employer will be formally declared. In letters to Magnus and Lord Cameron seen by the Guardian, Nick Smith, Labour’s shadow deputy leader of the House of Commons, called on both to provide greater transparency about Cameron’s pay and involvement with the Greensill-linked company the Gupta Family Group Alliance (GFG). GFG companies were Greensill Capital’s biggest clients before the scandal-hit firm collapsed in early 2021. Smith has asked Cameron to offer a full account of flights gifted to him during his employment at Greensill, including the mode and amount of payment he received. It comes after the Guardian revealed details of 13 flights that appeared to have been gifted to Cameron and payments understood to come via a trust in the tax haven of Guernsey created by Greensill. Cameron has always refused to reveal the means of payment and how much he received for his work lobbying for the scandal-hit company between 2018 and 2021. The former prime minister and officials were criticised last week for a lack of transparency in his declaration of ministerial interests, which confirmed only that he benefited from several trusts with interests in various sectors including mining and agriculture. Transparency conventions allow ministers to declare that they have a blind trust or blind management arrangement rather than offer any greater detail to the public. This has no legal definition and it often simply refers to an informal arrangement in which they do not make all day-to-day calls on commercial or financial decisions. These decisions can be made by close family members, including their spouse. The letters also ask Cameron to explain the nature and frequency of his meetings with the GFG founder, Sanjeev Gupta, who built a steel and energy empire spanning the US, UK, eastern Europe and Australia fuelled by funding from Greensill. They also ask that Cameron share correspondence and documents linked to the Greensill/GFG relationship and provide a full account of what he has shared about the two company groups with Magnus. Smith also asked whether investigations related to Cameron’s former employer in a range of jurisdictions including Switzerland and the UK will be detailed in future declarations of interest. There is an continuing criminal investigation into Lex Greensill and bankers at the now collapsed Credit Suisse, in Switzerland. On Tuesday, the Swiss financial regulator Finma bemoaned limits to its powers to scrutinise and punish any potential wrongdoing at financial institutions including Credit Suisse. The UK’s Serious Fraud Office is investigating GFG and its financial links to Greensill. The Cabinet Office and Foreign Office both declined to comment on specific points about Cameron’s current and potential future disclosures. The government instead directed the Guardian to a previous statement from Magnus: “The list is not a register of interests and does not therefore include every interest that a minister has declared in relation to themselves and their family members. “To do so would represent an excessive degree of intrusion into the private affairs of ministers that would be unreasonable, particularly in respect of their family members. The list instead documents those interests, including of close family, which are, or may be perceived to be, directly relevant to a minister’s ministerial responsibilities.”