(Adds further Obama comments, details of sanctions)
WASHINGTON, July 29 (Reuters) - President Barack Obama said on Tuesday the United States has expanded sanctions against Russia over its support for rebels in eastern Ukraine, unveiling the steps after the EU agreed to its own new measures against Moscow hours earlier.
Speaking at the White House, Obama said the new sanctions targeted "key sectors of the Russian economy" - energy, arms and finance.
Obama said the new U.S. sanctions block the exports of specific goods and technologies to the Russian energy sector, expand sanctions to include more Russian banks and defense companies, and formally suspend credit that encourages exports to Russia and financing for economic development projects in Russia.
"If Russia continues on this current path, the costs on Russia will continue to grow," Obama said.
The United States slapped sanctions on VTB, the Bank of Moscow, the Russian Agriculture Bank and the United Shipbuilding Corp over Moscow's support for separatists in eastern Ukraine, the Treasury Department said.
"Russia's actions in Ukraine and the sanctions that we've already imposed have made a weak Russian economy even weaker," Obama said.
"Major sanctions we're announcing today will continue to ratchet up the pressure on Russia, including the cronies and companies that are supporting Russia's illegal actions in Ukraine," Obama added.
The new U.S. action expanded the list of Russian banks subject to U.S. sanctions to almost all the largest banks with state ownership of over 50 percent, except for Sberbank .
The sanctions on the three banks prohibit U.S. citizens or companies from dealing with debt carrying maturities longer than 90 days, or with new equity. The sanctions on United Shipbuilding Corp, a shipbuilding company based on St. Petersburg, freeze any assets it may hold in the United States and prohibits all U.S. transactions with it.
The last round of U.S. sanctions, announced on July 17, hit Russia's largest oil producer Rosneft, its second largest gas producer, Novatek, and its third largest bank, Gazprombank, as well as other banks, prominent individuals and the weapons manufacturer Kalashnikov. (Reporting by Eric Beech and Will Dunham; Editing by Sandra Maler)