Police in Peru raided the homes of key government officials in Lima on Saturday as part of an investigation into allegations that President Martin Vizcarra obstructed a graft probe that will see him face impeachment proceedings next week.

Meanwhile, Vizcarra's cabinet accused the head of Congress, Manuel Merino, of trying to involve the country's military to oust him.

Merino, as parliament speaker, would act as interim president if Vizcarra is impeached.

Prime Minister Walter Martos and Defense Minister Jorge Chavez -- both retired generals -- claimed Merino had made calls to senior army chiefs as the impeachment process was launched and accused him of "recklessness" at a press conference on Saturday.

"We have witnessed a very serious event," Martos said.

The role of the armed forces is seen as key to stability in the resource-rich South American country should Vizcarra be removed from power.

Merino in turn accused the government of "trying to confuse the population, by making them believe that there is a plot."

The government have already accused lawmakers seeking Vizcarra's head of mounting a "coup d'etat".

Congress voted late Friday to open impeachment proceedings against Vizcarra for "moral incapacity" over accusations he incited aides to lie to investigators.

"Searches were carried out of eight properties of people under investigation and witnesses in the case of alleged irregularities in the hiring of Richard Cisneros Carballido as a consultant to the Ministry of Culture," the public prosecutor's office said in a statement.

Vizcarra, in power since 2018, came under fire after audio recordings were leaked in which he is heard telling aides to hide details of his office's hiring of Cisneros, a popular singer, as a paid cultural advisor.

The presidents of Bolivia, Colombia and Ecuador -- part of a regional political grouping with Peru called the Andean Community -- called on lawmakers to avoid impeaching Vizcarra in the midst of an economic crisis caused by the coronavirus pandemic.

"We call upon your authorities to avoid actions that could put at risk the legitimate exercise of power and the democratic political institutional process" in Peru, said a statement signed by Bolivia's Jeanine Anez, Colombia's Ivan Duque and Lenin Moreno of Ecuador.

Peru's Congress voted to open impeachment proceedings against President Martin Vizcarra (shown September 10, 2020) for "moral incapacity" over accusations he incited aides to lie to investigators
Peru's Congress voted to open impeachment proceedings against President Martin Vizcarra (shown September 10, 2020) for "moral incapacity" over accusations he incited aides to lie to investigators Peruvian Presidency / Carla PATINO

The political crisis further rattled an economy which has already seen second-quarter GDP slashed by 30 percent due to the effects of the coronavirus pandemic.

The Peruvian sol was the worst performing emerging economy currency on Friday, losing 0.8 percent against the dollar and forcing Lima's Central Bank to twice intervene to bolster the currency.

One of the properties searched is the home of a top presidential official, Miriam Morales. The home of another key assistant to Vizcarra, Karem Roca, was also raided.

Both feature on leaked audio tapes in which Vizcarra is heard talking about the scandal and inciting them not to cooperate fully with investigators.

Cisneros' home was also searched, as well as those of five officials from the culture ministry, which hired the singer between 2018 and this year for about $50,000.

Fourteen people are currently under investigation in the probe, led by provincial prosecutor Janny Sanchez Porturas.

All of them are being investigated for "aggravated collusion and incompatible negotiation to the detriment of the state," according to the Attorney General Office.

Vizcarra, 57, denied having intervened in the details of the singer's contract, whom he said he met during the 2016 election campaign.

Vizcarra was then a candidate for vice-president alongside Pedro Pablo Kuczynski, his predecessor who was forced to resign in March 2018, after impeachment proceedings were launched against him over a corruption scandal.

Following Friday's vote, the 130-member Congress is to hold an impeachment vote on September 18.

The president's opponents need 87 votes to remove him.

Vizcarra said he had done nothing wrong and was the victim of a "plot against democracy" in the South American country.

The president has won popular support for an anti-corruption crusade that has put him at loggerheads with opponents in Congress, including over a reform banning convicted criminals from standing for election.