SEOUL, July 25 (Reuters) - South Korea's constitutional court on Tuesday ruled against a parliamentary vote to impeach the interior minister over the response by the government to a deadly Halloween crush in the capital Seoul last year that killed more than 150 people.

While the court found minister Lee Sang-min had made remarks that were inappropriate, they did not amount to grounds for impeachment, it said in a statement.

The decision was unanimous, the court said.

"This disastrous incident was not caused and exacerbated by a single cause or person," Lee Jong-seok, a justice at the court said, adding that each government agency did not have the ability to respond in a united manner to major-scale disasters.

Minister Lee did not attend the court session and only his lawyers were present.

Lawmakers in February voted to impeach the minister, urging him to take responsibility for the botched response to the crowd surge that killed 159 people, many in their 20s, in a popular nightlift district in Seoul.

President Yoon Suk Yeol had rejected the opposition's demand that he sack Lee, and his office and ruling party denounced the Democrats and accused them of abusing their majority power to press ahead with the impeachment.

The presidential office said at that time that facts about the incident needed to be established first through an investigation, without directly commenting on Lee's fate.

In June, the opposition-led National Assembly decided to fast-track a bill aimed at launching an independent probe into the Itaewon crowd crush.

The Itaewon district in South Korea’s capital is known to revelers as a place of fun, freedom and openness. But its narrow, steep streets and constrained access points proved a lethal mix for Halloween partygoers who became trapped in a crowd crush that left more than 150 people dead.

More than 20 relatives of the victims of the crush circulated open letters this week urging the constitutional court to remove the minister from his post.

"We hope for a just society where those responsible apologize and step aside and preventative measures are introduced to ensure such a disaster never repeats," one letter read.