Former KGB officer Alexander Litvinenko developed a powerful animosity toward Vladimir Putin, accusing the Russian leader of fomenting war and consorting with criminal gangs, the agent's widow testified Monday.

Marina Litvinenko spoke at an inquiry into the death of the ex-intelligence officer, who fled to London in 2000. He died in November 2006 after drinking tea laced with radioactive polonium-210 at a London hotel.

On his deathbed, Alexander Litvinenko accused Putin, the Russian president, of ordering his killing.

British officials have also accused the Russian state of being involved in the killing and British police have identified two Russian men as the prime suspects. They deny guilt and Moscow refuses to extradite them.

Marina Litvinenko told the inquiry that during the 1990s her husband grew increasingly concerned about "dirty business" in the FSB, the successor to the Soviet KGB. She said a turning point came when her husband was working for the anti-terrorism unit of the FSB during the first Chechen War. He interviewed a 17-year-old Chechen who told him his whole class had enlisted to fight Russia.

"For Sasha, this was shocking," she said referring to her husband by a diminutive. It was "the first time he realized something (was) wrong in this war."

She said his concerns peaked when it was suggested that he kill Boris Berezovsky, a Russian oligarch who had fallen out with the Kremlin.

She said her husband met Putin, who was appointed director of the FSB in 1998, to complain about corruption, but came away thinking their talk "was not productive."

Alexander Litvinenko was arrested after accusing the FSB of plotting to kill Berezovsky at a 1998 news conference. He was released in late 1999 and fled Russia the following year.

Marina Litvinenko said the family settled in Britain after the U.S. refused to grant them asylum.

Marina Litvinenko said she, her husband and their son traveled to Turkey and asked for asylum at the U.S. Embassy in Ankara. When they were turned down, they bought plane tickets to Tbilisi, Georgia, via London. She said at London's Heathrow Airport, Alexander Litvinenko approached a police officer and said: "I am KGB officer and I am asking for political asylum."

Marina Litvinenko said from about 2004 her husband received monthly payments of 2,000 pounds (about $3,000) from British intelligence in return for "consulting work" about organized crime in Russia.

Berezovsky, who settled in Britain in 2001, also helped fund Litvinenko in London, covering his rent and paying for a book co-authored by Litvinenko that accused the FSB of bombing apartment buildings in Moscow and other cities in 1999. The attack was blamed on Chechen militants and helped trigger Russia's second war in Chechnya.

Litvinenko also accused Putin of having ties to criminal gangs when he was mayor of St. Petersburg and even called him a pedophile in a 2006 article after seeing a photo of Putin kissing a young boy's stomach.

Berezovsky, who continued to be a thorn in Putin's side, was found dead by hanging in March 2013. A British inquest failed to determine whether he had been killed or committed suicide.

The British government long rejected holding a public inquiry into Litvinenko's death, but reversed its position after a court challenge from Marina. Witnesses are giving evidence in public, but classified intelligence evidence will be considered in private by the judge overseeing the inquiry, Robert Owen.