The Mercosur Federation of Rural Associations, known as Farm, warned the discord over Paraguay's exclusion from the trade bloc and almost simultaneous confirmation of Venezuela's membership in the group posed a threat to Mercosur.
Paraguay was suspended from Mercosur after the country's Senate voted to impeach Fernando Logo and remove him from the presidency June 22. Lugo was succeeded by Vice President Federico Franco but Mercosur denounced the move as a coup.
Paraguay's suspension removed the main obstacle to Venezuela's confirmation as a full member. But the manner in which the events took place has upset critics who say due constitutional processes were ignored.
Argentina, Brazil and Uruguay, who spearheaded the suspension and facilitated Venezuela's admission, are unfazed by the outcry and are going ahead with Venezuela's full incorporation. The countries see Venezuela's membership as an economic opportunity because of oil-rich Venezuela's voracious consumer market.
Critics say Venezuelan President Hugo Chavez riles democratic elements who oppose his style of government.
The farmers fear the horse trading has been misguided and will damage Mercosur's prospects of building on recent negotiations with Europe on a free trade pact between the Latin American group and the European Union.
Earlier diplomatic moves to have Paraguay ejected from the Organization of American States, which has headquarters in Washington, faced opposition from the OAS which sent a fact-finding mission to Asuncion and announced it would give Franco time to organize democratic elections next year.
Paraguay was also suspended from the Union of South American Nations, which has less diplomatic weight than Mercosur. Farmers' groups sent their own fact-finding mission to Asuncion to ascertain facts.
A report published after the visit said Paraguay's suspension and Venezuela's admission could undo two decades of efforts to promote regional integration. The report said Franco's accession to power after Lugo's removal posed no apparent threat to Paraguay's democratic credentials.
"We were able to confirm that in Paraguayan territory there is clearly a peaceful atmosphere with rule of the law as well as full exercise of public liberties and rights," the farmers' group said.
The farmers' representatives also made a plea for an early resolution at the thirteenth session of the Agricultural Council of the South in Santiago, Chile.
The agriculture industry fears the crisis generated over Paraguay's suspension will set back trade talks with Europe.
The suspension is not without costs to countries that backed it, particularly Brazil.
At stake are Brazil's lucrative trade and energy relations with landlocked Paraguay, a country less well off than economic dynamo Brazil but still an important market for Brazilian exports and partner in Itaipu Dam power generation.
Brazilian President Dilma Rousseff has come under fire from critics who question her handling of Brazilian-Paraguayan diplomacy after Lugo's removal.
To complicate matters for the Brazil-led campaign against Franco's regime, critics point out that Lugo did, in fact, accept the congressional vote that removed him from the presidency.
Critics say the diplomatic move is set to become an embarrassment for Rousseff, Argentine President Cristina Fernandez de Kirchner and Uruguay President Jose Mujica as Franco's presidency settles into power.
Diplomatic moves to have Paraguay's ties with the European Union suspended have also remained inconclusive, while the EU adopts a conciliatory position that it hopes will steer Paraguay to democratic elections next year.
The three presidents have courted controversy in the manner in which they used Paraguay's suspension to admit Venezuela to full membership of Mercosur.
Paraguay's legislature was the last hurdle in the way of Venezuela's membership of Mercosur. The country's suspension from the trade bloc cleared the way for Venezuela's Mercosur membership to be ratified.
Paraguay's new government has accused Chavez of financing moves to destabilize the country.
Chavez is to fly next week to Brasilia to attend a meeting in which Venezuela will officially become a full member of Mercosur.
Chavez also faces tough negotiations over divergences between his foreign policy preferences and Mercosur's pragmatic stance. Chavez has built strong links with Iran and backed the country's nuclear program.