The embattled former national security adviser to Donald Trump failed to disclose thousands of dollars of income from Russian companies, documents show.

In a financial disclosure form on 11 February, Michael Flynn did not reveal he had speaking engagements, including for the state-funded RT channel and Volga-Dnepr Airlines.

The form, which was signed electronically, was released by the White House at the weekend.

Yet he did list these incomes in a form on 31 March, under a section called “sources of compensation exceeding $5,000 a year”.

The discrepancy could add to the legal battle Mr Flynn is about to face as he is due to testify before the Senate about his links to Russia and whether there was any collusion between the country and Trump aides to propel Mr Trump into the White House.

His lawyer has requested immunity from prosecution for his client if he testifies before the Senate and House intelligence committees. The request has reportedly been rejected.

“General Flynn certainly has a story to tell, and he very much wants to tell it," said his lawyer in a statement .

General Mattis: Russia has been 'mucking around inside other people's elections'

Mr Flynn was forced to resign after just 24 days in the job as he allegedly misled Vice President Mike Pence about his phone calls with Russian ambassador Sergei Kislyak before Mr Trump was in office.

Mr Trump said the media treated his disgraced employee “very badly” and said Mr Flynn had not been let go due to calling the ambassador, but due to an erosion of "trust".

New York City bodegas strike to protest Trump's travel ban Show all 27 1 /27 New York City bodegas strike to protest Trump's travel ban New York City bodegas strike to protest Trump's travel ban Ethnic Yemenis and supporters protest against President Donald Trump's executive order temporarily banning immigrants and refugees from seven Muslim-majority countries, including Yemen on February 2, 2017 in the Brooklyn borough of New York City. At least 1,000 Yemeni-owned bodegas and grocery-stores across the city shut down from noon to 8 p.m. today to protest the order. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban Men pray during a protest by ethnic Yemenis and supporters over President Donald Trump's executive order temporarily banning immigrants and refugees from seven Muslim-majority countries, including Yemen on February 2, 2017 in the Brooklyn borough of New York City. At least 1,000 Yemeni-owned bodegas and grocery-stores across the city shut down from noon to 8 p.m. today to protest the order. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban Ethnic Yemenis and supporters protest against President Donald Trump's executive order temporarily banning immigrants and refugees from seven Muslim-majority countries, including Yemen on February 2, 2017 in the Brooklyn borough of New York City. At least 1,000 Yemeni-owned bodegas and grocery-stores across the city shut down from noon to 8 p.m. today to protest the order. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban Men pray during a protest by ethnic Yemenis and supporters over President Donald Trump's executive order temporarily banning immigrants and refugees from seven Muslim-majority countries, including Yemen on February 2, 2017 in the Brooklyn borough of New York City. At least 1,000 Yemeni-owned bodegas and grocery-stores across the city shut down from noon to 8 p.m. today to protest the order. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People gather for evening prayer at a rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally with flags at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban People rally with flags at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally with flags at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally with flags at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally with flags at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest US President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban People rally at Brooklyn Borough Hall as Yemeni bodega and grocery-stores shut down to protest President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen, on February 2, 2017 in New York. Bryan R. Smith/AFP/Getty New York City bodegas strike to protest Trump's travel ban A Yemeni business owner places a sign on the gate of his store February 2, 2017 in the Brooklyn borough of New York City. Across the city, Yemeni owned bodega and grocery-stores will shut down from noon to 8 p.m. to protest President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen. It is expected that over 1000 stores will be closed in protest with workers and owners participating in an afternoon rally in Brooklyn. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban A Yemeni business owner places a sign on the gate of his store February 2, 2017 in the Brooklyn borough of New York City. Across the city, Yemeni owned bodega and grocery-stores will shut down from noon to 8 p.m. to protest President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen. It is expected that over 1000 stores will be closed in protest with workers and owners participating in an afternoon rally in Brooklyn. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban NEW YORK, NY - FEBRUARY 02: Yemeni business owner Musa closes the gate to his store February 2, 2017 in the Brooklyn borough of New York City. Across the city, Yemeni owned bodega and grocery-stores will shut down from noon to 8 p.m. to protest President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen. It is expected that over 1000 stores will be closed in protest with workers and owners participating in an afternoon rally in Brooklyn. Spencer Platt/Getty New York City bodegas strike to protest Trump's travel ban A Yemeni business owner closes the gate to his store February 2, 2017 in the Brooklyn borough of New York City. Across the city, Yemeni owned bodega and grocery-stores will shut down from noon to 8 p.m. to protest President Donald Trump's Executive Order banning immigrants and refugees from seven Muslim-majority countries, including Yemen. It is expected that over 1000 stores will be closed in protest with workers and owners participating in an afternoon rally in Brooklyn. Spencer Platt/Getty

He and Russian officials have flatly denied any collusion to tar Hillary Clinton. Mr Trump insisted Democrats are just sore over his win, and pointed to allegedly bias treatment of Ms Clinton's relationship with Russia.

Several congressional committees and the FBI are looking into alleged ties between the Trump campaign and Russia.

After Mr Flynn was forced to resign, other threads started to unravel. Jared Kushner, Mr Trump’s son-in-law and Senior Adviser, will also face questioning over his meeting with the ambassador and the head of a state-owned Russian bank.

Attorney General Jeff Sessions has recused himself from any Justice Department investigation of Russian links as he also admitted to meeting with Mr Kislyak.

