(Adds quotes from Blinken)
By Roberta Rampton and Steve Holland
WASHINGTON, July 28 (Reuters) - U.S. President Barack Obama and European leaders, in a show of solidarity, agreed on Monday to impose a wider set of sanctions against Russia's financial, defense and energy sectors in the wake of the shootdown of a passenger jet over Eastern Ukraine, a top Obama aide said.
The coordinated measures come as the United States warned of a Russian troop buildup along the border with eastern Ukraine and the shipment of new sophisticated weapons to pro-Russian separatists.
The new sanctions, which Obama and leaders of Germany, Britain, France and Italy discussed in a rare five-way conference call by video and phone, are aimed at increasing the pressure on Russian President Vladimir Putin.
"It's precisely because we've not yet seen a strategic turn from Putin that we believe it's absolutely essential to take additional measures and that's what the Europeans and the United States intend to do this week," said Tony Blinken, a national security adviser to Obama.
Obama and top aides have been working behind the scenes to convince European allies to impose sanctions against Russia that are on par with U.S. sanctions. Europe's response to Russian aggression in Ukraine has been more tepid than that of the United States because its economy is more entwined with Russia's.
Blinken told reporters existing sanctions have hurt Russia's economy, but have not been enough to force Putin to back off. Instead, Blinken said Russia has increased the supply of heavy weapons to the separatists.
"We've seen convoys of tanks, multiple rocket launchers, artillery, and armored vehicles. There's evidence it's preparing to deliver even more powerful multiple rocket launchers," Blinken said.
A Russian troop buildup on the border is also raising concerns that Russia could create a pretext for an incursion into eastern Ukraine to support the increasingly embattled rebels who have been blamed for shooting down a Malaysian passenger plane July 17.
"We've seen a significant rebuild up of Russian forces along the border, potentially positioning Russia for a so-called humanitarian or peacekeeping intervention in Ukraine," he said. (Reporting by Roberta Rampton; Editing by Doina Chiacu)