The United States and the European Union are widening sanctions against dozens of Russians and Ukrainian individuals and entities with connections to Crimea's annexation and the ongoing violence in eastern Ukraine.

In an announcement published in the U.S. Federal Register on September 2, the U.S. administration said it was adding 29 people to its sanctions list.

Some of those added have ties to Kremlin-linked insiders and companies who were previously sanctioned, including Gennady Timchenko, a wealthy oil trader believed to be close to President Vladimir Putin.

A total of 33 companies or other entities were cited, including subsidiaries of state-owned oil giant Rosneft, headed by Putin ally Igor Sechin, and the company that manufactures Kalashnikov assault rifles. Crimea's top ferry operator and several ports on the Black Sea peninsula, which was annexed by Russia in March 2014, were also blacklisted.

Among other things, the sanctions, imposed by the Commerce Department, make it more difficult for the companies and individuals to get export licenses for goods and materials from the United States.

The European Union, meanwhile, said it would extend the freezing of assets and visa bans for 150 Russians and Ukrainian separatists, along with 37 companies and entities either located in Crimea or having ties to separatist units in eastern Ukraine.

The announcement expands the sanction list first imposed last year by the 28-member bloc, and had included other top Russian officials such as Deputy Prime Ministers Dmitry Rogozin and Dmitry Kozak.

In Moscow, the Foreign Ministry called the new sanctions illegitimate and added to "hostile actions" taken by the United States against Russia. Moscow warned it would respond with unspecified retaliatory measures.

"The action of the United States devalues the signals that it is interested in cooperating with us in resolving myriad pressing international problems," the ministry said in a statement. "The United States should have no illusions that it could continue this course without negative consequences for themselves," it said.

"This reckless course is of growing concern even among U.S. allies," the ministry added. "Retaliatory measures, while not necessarily reciprocal, will follow from our side."

Kremlin spokesman Dmitry Peskov also promised a response.

Оther top Russian and Ukrainian officials who were previously sanctioned by the United States include Vladislav Surkov, an influential aide to Putin; Valentina Matviyenko, head of Russia's upper house of parliament; and Viktor Yanukovych, the Ukrainian president who was ousted amid violent protests in Kyiv in February 2014.

The crisis in Ukraine has sent relations between the West and Moscow to lows not seen since the Cold War. Russia has struggled to prop up Crimea's economy, which is now all but cut off from Ukraine. Fighting in eastern Ukraine has ebbed in recent days, according to international observers.

More than 6,400 people are estimated to have died in the conflict.

Despite the gravity of the crisis, the efforts of Washington and Brussels to influence Moscow to reverse the annexation and stop its backing of separatist forces have been mixed at best.

In a report last month, the International Monetary Fund (IMF) estimated that the Western sanctions, and the retaliatory measures taken by the Kremlin, had reduced Russia's real gross domestic product by between 1 and 1.5 percent. In the medium run, the measures could result in a drop in cumulative output of up to 9 percent of GDP, though the IMF cautioned that wasn't a certainty.

Other economists, however, have said the precipitous drop in global oil prices, from which Russia's budget derives a substantial chunk of revenue, has had a greater impact on Moscow's behavior than sanctions.

With reporting by Reuters