By Steve Holland and Jeff Mason
WASHINGTON, Feb 24 (Reuters) - President Joe Biden was poised to unveil harsh new sanctions against Russia on Thursday after Moscow attacked Ukraine by land, air and sea, triggering condemnation and financial penalties from the United States and its allies.
Biden will announce the new measures at 1:30 p.m. EST (1830 GMT), the White House said.
Biden met with his counterparts from the Group of Seven allies earlier on Thursday to map out more severe measures against Russia after President Vladimir Putin launched what Biden called "a premeditated war" against Ukraine.
Biden, who spoke with Ukrainian President Volodymyr Zelenskiy late on Wednesday, also convened his National Security Council on Thursday to discuss the situation.
His announcement will represent the second tranche of sanctions against Russia since Putin earlier this week declared two breakaway regions of Ukraine independent and sent troops there.
The United States had warned it would initiate waves of sanctions against Moscow if it further invaded Ukraine, and Russia's full-on military assault launched on Thursday led to the latest round of Western penalties.
Britain unveiled new measures targeting banks, members of Putin's inner circle and the very wealthy who enjoy high-rolling London lifestyles. Prime Minister Boris Johnson told parliament that leaders had agreed to work together to "maximise the economic price" Putin will pay.
On Wednesday Washington imposed sanctions on the company in charge of building Russia's Nord Stream 2 gas pipeline, and on Tuesday it sanctioned two large Russian financial institutions and Russian sovereign debt along with some members of the Russian elite and their family members.
The United States imposed the sanctions in cooperation with Western allies.
Biden had faced political pressure at home to impose sanctions before Putin invaded. The White House has held open the door to diplomacy, even agreeing in principle earlier to a summit between the president and Putin if Russia did not invade.
The president now becomes the face of the Western response to Russian aggression at a time when he is battling low poll numbers at home, rising inflation that could be exacerbated by the Ukraine conflict, and looming midterm elections that could hand control of the Senate and House of Representatives from his fellow Democrats to Republicans.
The White House has warned Americans that the conflict could lead to higher fuel prices in the United States, though it is taking measures to help soften that blow. U.S. officials have been working with counterparts in other countries on a combined release of additional oil from global strategic crude reserves, two sources said on Thursday.
Members of Congress from both parties urged the White House to move swiftly on tougher actions against Russia, including providing military aid to Ukraine, imposing stringent sanctions and export controls and ousting Russia from international organizations.
"This unprovoked attack has brought into sharp focus the need to expel the current Kremlin leadership from the international community," said Senator Bob Menendez, Democratic chairman of the foreign relations committee. "Today must mark a historical shift in how the world views and deals with the despot in Moscow." (Reporting by Steve Holland and Jeff Mason; Additional reporting by Andrea Shalal and Patricia Zengerle; Editing by Daniel Wallis)