Marina Litvinenko, Alexander's widow (pictured), writing in the International Herald Tribune:

Today leaders from around Europe will gather in Lisbon to meet with Vladimir Putin, the Russian president, for the EU-Russia summit. I can only imagine there is much to discuss, from the state of democracy in Russia to energy matters, to Kosovo to Iran. But there is one more glaring issue, which simply cannot be ignored at the meeting - the murder last year in London of my husband, Alexander Litvinenko with radioactive Polonium 210. He was murdered by the most cruel method imaginable.

Horrendous though it was, this was not even just the murder of one man - it was an act of nuclear terrorism on Europen soil. A mass radioactive poisoning took place in the center of London. Hundreds of others were exposed. Restaurants, hotels, aeroplanes and offices were contaminated. Several people including myself have an increased risk of developing cancer due to the exposure that we received.

In the eleven months since my husband's death, there has been a real and full investigation by British police. This was finished in January and the Crown Prosecution Service decided there was enough evidence to charge Andrei Lugovoy with my husband's murder. The British Government then requested Mr Lugovoy's extradition from Russia. Russia has refused to extradite him. In retaliation, Britain has tightened the visa regime for Russian officials and expelled four diplomats believed to be Russian intelligence officers in London. I am assured by British officials that they will continue to press Russia to give up the suspected murderer who must stand trial in Britain.

In the meantime Mr Putin has taken a defiant position. He spoke on national television in rejection of the British request using the most rude and uncivilized language. He advised "the British to get a brain change." He dismissed the Scotland Yard's evidence as insufficient. Effectively he has given Mr Lugovoy his personal endorsement in the eyes of the Russian people and the world. His propaganda machine went on to turn Mr Lugovoy into a kind of national hero. So, the accused murderer is now running for the Russian Parliament. Mr Putin's standing up for Mr Lugovoy adds credence to the allegations that Russia has something to hide. Indeed, Mr Lugovoy had no motive for killing my husband and only the highest level of the Russian government could authorize access to Polinium-210, one of the most toxic substances in the world.

Perhaps the real reason why Mr Lugovoy cannot be allowed to stand trial is that he would name those who provided him with Polonium and sent him on his mission to London? Where does this leave me and my son? We need to see justice. I owe it to my husband to demand that justice is done. I also owe it to the good people of Britain, the London police and the British government, who all stood by me, to do my utmost that our common quest for justice is not ignored by the outside world. That is why I will be in Lisbon as the EU-Russia summit begins. I have a direct message for President Putin: this will not go away as long as I live.

I will also have a serious message for EU leaders: it should be impossible for you to sit around a table with Mr Putin without demanding that he co-operate with Britain. I know that the EU has made statements on the Litvinenko case before, but we have now moved beyond words. The EU needs to take action and move from statements to sanctions in solidarity with Britain.