Two businesses owned by Tony Blair have amassed a cash pile of more than £13m after a key part of his empire enjoyed a jump in profits.

New accounts filed with Companies House reveal that one venture in the former prime minister's complex network of financial legal entities saw profits jump almost 50% to just below £2m.

Since stepping down from politics in 2007, Blair has received millions of pounds from a mix of business interests that include advising governments, consultancy work for US investment bank JP Morgan and the lucrative international speaking circuit.

He has insisted he does not want to be "super-rich", and has said his income pays for philanthropic projects, including development work in Africa and an inter-faith charity. But after rapidly becoming one of the highest paid public speakers in the world and flying around by private jet he has faced some criticism for his lifestyle.

Blair's properties include a multimillion-pound London home and a country retreat once owned by the late Sir John Gielgud, bought for £5.75m .

Windrush Ventures, the ultimate owner of which is Blair, made profits of £1,995,000 in the year to the end of March 2013, up £649,000 from a year earlier. The company, which provides "management services", holds £8.8m in cash. The company now employs 35 people and has a wage bill of £3m, equal to £85,000 per employee.

Smaller company Firerush Ventures, with less detailed accounts also filed with Companies House and are published on the Office of Tony Blair website, has £4.6m in cash.

Blair's office pointed out that the reports do not show the former Labour PM's own earnings. It said in a statement: "These are the financial statements of the two companies through which the operating costs of the Tony Blair group's global activities are paid. They do not represent his earnings or the earnings or the profit of his businesses and are not referable to them. They do not represent either the accounts of his charities or his donations to them."

The statement also said the businesses pay full corporation tax , adding: "The money made by Mr Blair from the Windrush and Firerush businesses is not published in these accounts; it is though, subject to full personal income tax. and that the former prime minister

"Mr Blair continues to be a UK taxpayer and pays full personal tax on all his earnings worldwide."

One of Blair's most high-profile ventures has been advising the Kazakh government under a contract with Tony Blair Associates.

His involvement with a regime denounced by Amnesty International over its "disgraceful" record on human rights has drawn criticism. But Blair has said he is working with the government to push through a programme of political and economic reform.

The jump in profits at Blair's Windrush is in contrast to the financial fortunes of George Osborne's family business revealed in the latest filings to Companies House. The upmarket fabrics and wallpaper company Osborne & Little, which is chaired by the Conservative chancellor's father, Sir Peter Osborne, suffered widening losses of nearly £750,000 before tax, blaming a "poor worldwide economic climate".