The European Union has tightened sanctions meant to punish Russia for its role in the crisis in Ukraine, a move Moscow said could undermine efforts to end a five-month conflict that has killed more than 3,000 people.
The new sanctions include asset freezes and travel bans on senior officials and lawmakers and restrictions on financing for some state-controlled Russian companies.
The companies targeted include Russia's largest oil producer, Rosneft, as well as pipeline operator Transneft and Gazprom Neft, the oil unit of natural gas monopoly Gazprom.
The measures were formally imposed upon publication in the "Official Journal of the European Union" on September 12.
European Council President Herman Van Rompuy said on September 11 that they could be scaled back or repealed, and that the EU would monitor thepeace process in eastern Ukraine to determine before the end of September if changes are merited.
Ukrainian President Petro Poroshenko welcomed the new sanctions, saying they demonstrated the level of European solidarity with Ukraine in its confrontation with Moscow and pro-Russian separatists.
The United States, in a move coordinated with the EU, is also due to unveil new sanctions against Russia on September 12.
President Barack Obama, in a statement on September 11, said the United States is implementing the new measures "in light of Russia's actions to further destabilize Ukraine over the last month, including through the presence of heavily armed Russian forces in eastern Ukraine."
Obama said that if Russia "fully implements its commitments," the U.S. sanctions could also be rolled back.
A NATO official said on September 11 that Russia still had at least 1,000 soldiers in eastern Ukraine, despite a September 5 cease-fire deal between Kyiv and the rebels
Russia denies Western accusations that it has sent troops and weapons to help the rebels.
Foreign Minister Sergei Lavrov said imposing the sanctions "at the very moment when the peace process is gaining stability...means choosing the path of disrupting the peace process."
He said Russia would respond "calmly, adequately and most of all from the need to protect our interests."
On September 11, the Foreign Ministry called the planned sanctions an "unfriendly act" and said Russia's response would be "absolutely proportionate."
The Russian companies targeted by the latest EU sanctions include United Aircraft Corporation, the parent company that produces MiG and Sukhoi fighter jets, tank maker Uralvagonzavod, helicopter maker Oboronprom, as well as the manufacturer of Kalashnikov rifles.
The 24 individuals added to the list of people targeted by EU sanctions include eastern Ukrainian separatist leaders, several leading Russian lawmakers, including nationalist firebrand Vladimir Zhirinovsky, as well as Sergei Chemezov, the head of arms and technology holding Rostec.
The latest additions bring to 119 the total number of people sanctioned by the EU over the Ukraine conflict.
The measures were agreed by EU leaders on the sidelines of a NATO summit on September 5 and formally approved in Brussels on September 8.
But publication of the decision was delayed to allow time to assess the implementation of a cease-fire agreement in eastern Ukraine between Kyiv and pro-Russian separatists.
Poroshenko said the Ukrainian and the European parliaments would both meet on September 16 to ratify Ukraine's EU Association agreement.
He called the planned simultaneous ratification of the accord by the two parliaments a "historic moment" that defines his country's future.
He also told an international conference in Kyiv on September 12 that he hoped to secure a "special status" for Ukraine with NATO during his visit to Washington next week.