WASHINGTON, July 20 (Reuters) - Belarus opposition leader Sviatlana Tsikhanouskaya said on Tuesday that she asked U.S. officials to impose sanctions on companies in her country"s potash, oil, wood and steel sectors, as she visited Washington seeking stronger action against President Alexander Lukashenko"s government. Such measures would go beyond existing sanctions on Lukashenko"s political allies and government bodies and "will be a real hit on him, to make him change his behavior and to release political prisoners," Tsikhanouskaya told reporters. She said she delivered the list of enterprises, among them state-owned producer of potash fertilizer, Belaruskali, at a meeting on Monday with State Department officials including Secretary of State Antony Blinken. read more On Tuesday during a webinar sponsored by the Atlantic Council think tank, Tsikhanouskaya called for much tougher action by the world"s democracies against Lukashenko, who has kept a tight grip on Belarus since 1994 and cracked down on peaceful street protests that began over a disputed presidential election last August. "I think it"s high time for democratic countries to unite and show their teeth," Tsikhanouskaya said. She met with White House national security adviser Jake Sullivan, who conveyed U.S. "respect for the courage and determination of the opposition" in Belarus, National Security Council spokesperson Emily Horne said in a statement. "The United States, together with partners and allies, will continue to hold the Lukashenka regime accountable for its actions, including through the imposition of sanctions," the statement said. Tsikhanouskaya, 38, was a candidate in the election instead of her husband Sergei Tsikhanouskiy, a video blogger who has been jailed since May 2020 on charges such as violating public order, which he denies. Tsikhanouskaya fled to neighboring Lithuania after Lukashenko"s crackdown. Lukashenko"s opponents say the election was rigged so he could retain power. He denies the allegation. Meanwhile, the government has detained thousands of people amid allegations of torture, and shuttered independent media and rights groups. Tsikhanouskaya called for Russian President Vladimir Putin to stop supporting Lukashenko. "The relationship of Russia and Belarus at the moment is so close that the next step is loss of independence," she told reporters. "We understand that Lukashenko has to pay for the support of the Kremlin."