Russia has announced sanctions against senior Ukrainian officials as well as business and cultural figures, including the former prime minister Yulia Tymoshenko, the frontrunner for Ukraine’s 2019 presidential elections.

The Russian measures were presented as counter-sanctions after Ukraine targeted Russian officials and businesses earlier this year. The conflict goes back to Russia’s 2014 annexation of Crimea and its backing for separatists in south-east Ukraine.

The Russian prime minister, Dmitry Medvedev, on Thursday announced a list of 322 names – including the son of the Ukrainian president, Petro Poroshenko – and 68 companies that would be barred from doing business in Russia and whose assets would be frozen if they had them in Russia.

Russia also sanctioned leading Ukrainian security officials. Among them were Ukraine’s right-leaning interior minister, Arsen Avakov, the head of Ukraine’s national security and defence council, Oleksandr Turchynov, and the head of Ukraine’s SBU security service, Vasyl Hrytsak.

While Poroshenko was not sanctioned, those close to him were. They included the head of his presidential administration and his son Olexiy, who is a member of Ukraine’s parliament and also served during the conflict in south-eastern Ukraine.

The Kremlin spokesman, Dmitry Peskov, on Thursday said that Poroshenko was not included on the list because traditionally countries do not sanctioneach other’s heads of state. Tymoshenko is currently projected to enter a runoff with Poroshenko in presidential elections scheduled for March 2019, potentially setting up a scenario where Ukraine’s head of state could be under Russian sanctions.

Also on the list was Victor Pinchuk, the billionaire steel magnate. He is worth $1.4bn (£1.1bn), according to Forbes. Pinchuk, who organises an influential annual political conference in Kiev, also attracted scrutiny from the US special counsel investigation for a $150,000 (£116,000) donation to the Donald J Trump foundation made in 2015, according to the New York Times. The donation was reportedly for a 2015 speech by video link at a conference in Kiev.

Most Ukrainian leaders are believed to have cut their financial ties with Russia, and the sanctions may be designed to apply political pressure if it emerges that they still hold assets there.

The list also included Mustafa Dzhemilev, the veteran Crimean Tatar leader who was targeted after Russia’s takeover of Crimea.

Russia has sought a way to respond to foreign sanctions, which its president, Vladimir Putin, and other senior officials have described as economic war.

The sanctions list came a day after Putin announced Moscow would step up its efforts to support ethnic Russians abroad, which is how the Kremlin has justified its actions in Ukraine. Putin said he would cut red tape to make it easier for “compatriots” who wanted to resettle in Russia to get citizenship. Hundreds of thousands of eastern Ukrainians have resettled in Russia since 2014 and the new measures appear targeted at them.

While relations between Russia and Ukraine have collapsed since 2014, the countries remain important trading partners. Some of the sanctions appeared designed to target Ukrainian exports such as metals, poultry and a sunflower oil.