By David Brunnstrom and Matt Spetalnick

WASHINGTON (Reuters) - The United States on Thursday sanctioned two China-based shipping companies it says helped North Korea evade U.S. and international sanctions over its nuclear weapons programme, the first such steps since U.S. President Donald Trump and North Korean leader Kim Jong Un's summit meeting collapsed last month.

The U.S. Treasury also issued an updated advisory that listed 67 vessels that have engaged in illicit transfers of refined petroleum with North Korean tankers or were believed to have exported North Korean coal.

The Treasury Department identified the newly sanctioned firms as Dalian Haibo International Freight Co Ltd and Liaoning Danxing International Forwarding Co Ltd, both based in China.

The move prohibits U.S. dealings with the designated companies and freezes any assets they have in the United States.

The U.S. announcement came weeks after a second summit between Trump and Kim, in Hanoi, broke down late last month over conflicting demands by North Korea for relief from tough sanctions and from the U.S. side for North Korea to give up its nuclear weapons.

The United States has led international efforts to press North Korea through sanctions to give up its nuclear and ballistic missile programs.

"The United States and our like-minded partners remain committed to achieving the final, fully verified denuclearization of North Korea and believe that the full implementation of North Korea-related U.N. Security Council resolutions is crucial to a successful outcome," Treasury Secretary Steven Mnuchin said in the statement.

"Treasury will continue to enforce our sanctions, and we are making it explicitly clear that shipping companies employing deceptive tactics to mask illicit trade with North Korea expose themselves to great risk.”

LIMBO

U.S.-North Korean engagement has appeared to be in limbo since last month's summit breakdown.

Washington has said it aims to re-engage with Kim, but North Korea has warned it is considering suspending talks and may rethink a freeze on missile and nuclear tests in place since 2017 unless Washington makes concessions.

On Monday, two senior U.S. senators called for the Trump administration to correct a slowing pace of American sanctions designations on North Korea, saying there had been a marked decline in such actions during the past year of U.S. diplomatic engagement with Pyongyang.

They pointed to a 2019 U.N. report which found that North Korea had continued to defy U.N. sanctions with a massive increase in smuggling of petroleum products and coal and violation of bans on arms sales.

The Treasury statement said Dalian Haibo was targeted for dealings with Paeksol Trading Corp, a company previously designated by U.S. sanctions on North Korea.

It said Dalian Haibo shipped cargo from Dalian, China to Paeksol in Nampo, North Korea, in early 2018 aboard North Korean-flagged vessels.

The statement said Liaoning Danxing had "routinely used deceptive practices" to enable the work of North Korean procurement officials based in the European Union.

The Treasury statement said evasion tactics employed by North Korea included disabling or manipulating automated identification systems, physically altering vessels, transferring cargoes between ships and falsifying cargo documentation.

It said ports visited by vessels involved in ship-to-ship transfers included those in Taiwan, China, Russia and South Korea.

The Treasury Department said that in 2018, North Korean ports received at least 263 tanker deliveries of refined petroleum via U.N.-prohibited ship-to-ship transfers.

It said that if the tankers were fully laden, North Korea would have imported 3.78 million barrels - more than 7-1/2 times the 500,000 barrels per year allowed under a U.N. resolution.

Trump's national security adviser, John Bolton, said early this month that the United States would look at ramping up sanctions on North Korea if Pyongyang did not scrap its nuclear weapons programme.

U.S. Secretary of State Mike Pompeo said on March 4 he was hopeful he could send a team to North Korea "in the next couple of weeks," but there has been no sign of direct engagement since the failed Feb. 27-28 summit.

(Reporting by Doina Chiacu and David Brunnstrom; editing by Bernadette Baum and Jonathan Oatis)