By Nelson Bocanegra

BOGOTA Colombia's lower house on Monday said it would freeze debates on government-backed social reforms, as former high-ranking officials in President Gustavo Petro's administration were called to give evidence over alleged campaign financing irregularities.

The government of leftist Petro, who took office last year, has sent proposed labor, pension and health reforms - key policy promises - to Congress for approval.

The freeze in debate makes it unlikely the bills will win approval before the end of the legislative session on June 20, pausing their progress at least until the new legislative session begins a month later.

The debates "cannot be affected by external factors that could lead to an outcome that isn't positive for the country," David Racero, president of the chamber and a member of Petro's congressional coalition, told journalists.

Petro accepted the resignations of both his former chief of staff Laura Sarabia and the former ambassador to Venezuela Armando Benedetti last week, after the attorney general's office said two former employees of Sarabia were victims of illegal phone taps after she reported the theft of $4,000 from her home.

Benedetti was accused of leaking information from one of the ex-employees to the press, which he has denied. Sarabia has also denied any wrongdoing.

Over the weekend a local magazine published audio messages that Benedetti allegedly sent to Sarabia, who worked for him when he was a congressman.

In one recording Benedetti uses phrasing that media outlets and politicians have interpreted as being related to campaign finance irregularities, though Benedetti said on Twitter the audio was "manipulated".

Petro denied any financing irregularities via Twitter.

The National Electoral Council said in a document it has called Benedetti and Sarabia to give evidence on the allegations on June 13.

"We are entering a limbo of ingovernability because of the scandals that mean the government has to give explanations," said lawmaker Ciro Ramirez, of the opposition Democratic Center.

The government says the pension bill would strengthen the state pensions administrator and the labor reform would reduce working hours. Critics argue they could negatively impact Colombia's finances and hurt job creation.

The health reform, meant to increase access, has already prompted several ministerial changes.

"These scandals clearly undermine the government's credibility," said analyst Sergio Guzman of Colombia Risk Analysis, adding market uncertainty may increase.

(Reporting by Nelson Bocanegra; Writing by Oliver Griffin; Editing by Chizu Nomiyama)