BUENOS AIRES (Reuters) -An Argentine judge was assigned on Monday to investigate legal cases against President Javier Milei after the libertarian leader touted a cryptocurrency that crashed soon after, a case the country's fintech chamber said could amount to a "rug pull."

A rug pull is a scam in which developers lure in investors, causing a coin's value to rapidly shoot up, then quickly withdraw their funds, causing the cryptocurrency to lose its value and investors to be left with worthless tokens.

Milei later deleted his X post recommending the little-known crypto coin $LIBRA and said he had no relation to the cryptocurrency, but opposition lawmakers have said that Milei could face an impeachment trial in Congress over his actions.

Argentina's benchmark S&P Merval stock index was down nearly 4% in Monday trading, after initially tumbling nearly 6%.

The investigation was assigned on a random basis to veteran Federal Judge Maria Servini, after local media reported that more than 100 complaints were presented to the judiciary.

The token was launched on a crypto exchange called Meteora, the same platform that launched the $Trump meme coin in January, a cryptocurrency that saw a rapid surge and slump in which an estimated 200,000 crypto wallets lost money.

Meteora co-founder Ben Chow said in a post on X on Saturday that his team was "not involved in the deploy, the market making, or determining the launch of $LIBRA," adding that the firm "never had any access to the tokens or to Milei."

Chow added in a later post on Monday that the firm "had no involvement in the project at all beyond providing IT support, including commenting on the liquidity curve and helping verify the token's authenticity after the token was publicly launched."

Analysts said the opposition is unlikely to garner the votes to push through an impeachment proceeding. Accusations of fraud however, and Milei's direct involvement, could prove challenging as his government faces mid-term elections this year. An ongoing investigation, analysts added, could be a political opportunity for the opposition that is trying to make up ground on Milei, who has had a strong first year.

Some investors reacted on social media over the weekend in anger, saying they had been scammed out of their savings by the president of Argentina, while Milei's supporters defended him as the victim of politically motivated attacks.

"Irresponsible promotion of assets puts thousands of people at risk," ONG Bitcoin Argentina, a local educational non-profit, said over the weekend. "We take a stand against this fact and reaffirm the importance of education and transparency."

Milei himself came out swinging in face of criticisms.

"To the filthy rats of the political caste who want to take advantage of this situation to do harm, I want to say that they confirm every day how vile politicians are, and this increases our conviction to kick them in the ass," Milei said in a post on Friday in which he said he had deleted his original post.