St. Petersburg, Russia (CNN) -- Russia's President Vladimir Putin on Friday criticized Western nations for failing to ensure that weapons it plans to supply to Syrian rebels do not fall into the hands of al Qaeda.
"Where will those weapons end up," Putin told the St. Petersburg International Economic Forum, which was moderated by CNN's John Defterios. Putin questioned how weapons could safely be supplied to rebels if the U.S. recognized one of the key opposition groups was al Qaeda's affiliate Jabhat al-Nusra.
"If the United States and the State Department recognize that one of the key opposition organizations al-Nusra is a terrorist organization officially recognized as terrorist which is linked to al Qaeda, how can they give weapons to that part of the opposition?" he said.
"There are no answers to those questions... so it is not as simple as some people would suggest. We believe that our position is well founded ... we believe only the Syrian people themselves can guarantee a long-term solution."
His comments came as Syrian rebels said Friday they have received heavy weapons -- including anti-tank and anti-aircraft missiles -- from "brotherly nations that support the Syrian revolution."
At the G8 summit in Northern Ireland this week, Putin came under intense pressure to back plans to sideline Syrian President Bashar al-Assad. Putin is the only G8 leader who supports the Assad regime and during the meetings U.S. President Barack Obama said the two had "differing perspectives" but shared an interest in ending the violence.
On Friday, Putin laid it out more starkly: "There is indeed a certain difference of view between us and, let's say, the U.S.," he said.
The G8 summit came days after the U.S. pledged to play a greater role in assisting Syrian rebels, citing evidence that al-Assad's regime used chemical weapons against the rebels and his own people.
But Putin declared that he would not risk arms getting into the hands of rebels who "who kill their enemies and eat their organs," referencing a widely circulated video that purports to show a rebel fighter eating the heart of a dead soldier.
Putin reiterated his determination Friday to seek a peaceful outcome. "We should encourage the sides, the parties to the conflict to engage in dialogue and achieve positive results," he said. "This discussion was among interested parties among partners and there were differing opinions during that debate ... despite the depth and complexity of the problems, we were looking for a way to compromise."
The Russian leader also laid out plans to boost his country's anemic economic growth and crack down on tax evasion following promises made at the G8 meeting.
Putin was speaking alongside German Chancellor Angela Merkel, who said she had a "certain degree of skepticism" over Turkey's accession to the European Union after the government's heavy-handed approach to protestors.
Merkel said she was "shocked to see how the authorities dealt with demonstrators."
Turkey has been wracked by more than two weeks of protests against the government of Prime Minister Recep Tayyip Erdogan.
Merkel said discussions centred on whether it was the right time for Turkey to join, but that was "a totally different issue than whether the whole process as such will be stopped."
Putin said Russia would be tracking corporate accounting but would also look to create new investment opportunities.
He added that the country's plans to create "dynamic economic growth" which needed a balance between long terms goals and urgent issue. He said the country needed to increase its labor productivity, promote investment and innovation.
Putin said the country's tax policy should be working to develop business incentives, modernize business and create high quality jobs.
However, he said, "this is not the end of the course." The country would also look closely at "policy fiscal accounting and book keeping ... we have been talking about that for a long time."
Putin added: "Developing our tax policy is not justification for an increase in tax burdens for business."
Putin will be chair of the G-20 summit in September, following from the G8 summit of major developed nations.
At the G8 -- made up of UK, U.S., Germany, Russia, France, Italy, Japan and Canada -- the leaders also agreed to step up efforts to make individuals and companies pay the taxes they owe.
Stung by mounting evidence that major companies are shifting profits across borders, G8 leaders said countries should change rules to prevent that from happening and multinationals should report what tax they pay and where.
Tackling illegal tax avoidance has become increasingly important for governments as they struggle to revive their economies while paying down debt levels that exploded in the wake of the global financial crisis.
Pressure has intensified in the wake of Federal Reserve chairman Ben Bernanke's suggestions this week the stimulus program could be scaled back this year and end it completely in 2014. Stock markets around the world sank, including by nearly 4% in Russia.