* Putin greets Clinton with litany of trade complaints
* PM complains of U.S. sanctions on Russian firms
By Arshad Mohammed
NOVO-OGARYOVO, Russia, March 19 (Reuters) - Russian Prime Minister Vladimir Putin warned U.S. Secretary of State Hillary Clinton on Friday that full cooperation with the United States was impossible unless Russia was let into the World Trade Organisation.
At his first meeting with Clinton since she was appointed as Washington's top diplomat, Putin listed a litany of economic complaints against the United States and said Russian companies needed more assistance to penetrate the American market.
Putin, speaking to Clinton at the end of her two-day trip to Russia, said trade between the former Cold War foes had more than halved last year to $16 billion from $36 billion and scolded her for U.S. sanctions against Russian companies.
Russia's most popular politician, who stepped down as president in May 2008, reminded Clinton that Russia remained outside the WTO, more than 17 years after beginning its bid to join the 153-member body.
"We have been negotiating this issue for 17 years now," Putin told Clinton. "Three questions remain and yet we keep on going round and round this triangle. But these questions really have no serious significance for the U.S. economy."
Putin complicated Russia's WTO membership bid last year by saying it would only join along with Belarus and Kazakhstan. Moscow has since sent conflicting signals on the issue.
"We are very committed to Russia joining the WTO and have spoken with the president and cabinet members about how we can help to facilitate that happening," Clinton said.
Putin told Clinton that the WTO bid needed to be resolved before full cooperation with Washington could take place, his deputy chief of staff, Yuri Ushakov, told reporters.
"If we really want to cooperate then this question (WTO entry) needs to be resolved," Ushakov was quoted as saying by Russian news agencies. "This question depends on the political will of the Washington administration."
More than a year after Barack Obama launched an effort to "reset" ties with Moscow, bilateral trade has plummeted, a major arms reduction agreement remains unsigned and Moscow is still unhappy about U.S. plans for a missile defence shield in Europe.
Putin did offer some hope on the relationship, saying that common ground had been found on some of the biggest issues.
"Despite some differences on particular issues, we have been able to reach agreement on most important ones," he said, though he also rapped Clinton for U.S. sanctions against Russian firms.
"Five Russian companies are still under the sanctions that were initiated by your very agency," Putin said.
A senior U.S. official said he not know precisely which sanctions Putin referred to, but said he assumed they were U.S. government sanctions against companies believed to have violated U.S. non-proliferation rules.
The official, who spoke on condition his name was not used, said he suspected Putin was referring to companies that may have sold prohibited technologies to Iran, North Korea or Syria.
Putin said that companies such as General Electric Co and Boeing Co had been working well in Russia for years.
He then asked for U.S. help to smooth the path into the U.S. market for Russian companies such as metals giant Norilsk Nickel and steelmaker Severstal.
"They of course need escorting. They need signals that they are welcome," Putin said. He added that the United States ranked eighth in terms of investment in Russia. "This is not much." (Writing by Steve Gutterman and Guy Faulconbridge; editing by David Stamp)