A total of 44 people put their name on Sunday to a seven-point statement that hit out at general poor organization along with a lack of transparency by the Spanish federation (RFET).
It emphasized the "chaotic" and "belligerent" way that the federation is led by president Jose Luis Escanuela and asks that the "necessary authorities" take swift action to remedy the situation.
The letter comes on the back of claims in local media that the nation's first female Davis Cup captain Gala Leon offered her resignation following continued disapproval of her appointment last September, but it was not accepted by the federation.
Nadal was among those who reacted with disbelief at the RFET's naming of Leon, who had a career-high ranking of 27 as a player, to replace Carlos Moya.
It has led to accusations of sexism and Nadal himself admitted over the weekend that the controversy is tarnishing the image of Spanish tennis.
"The situation is terrible," Nadal told a news conference ahead of the Wimbledon.
"All these things that are happening cause damage to tennis, to the desire sponsors might have to invest in our sport, to the excitement that kids might have in continuing to play," added the 14-times grand slam champion.
There has also been a standoff between the government sports council (CSD), which has questioned Leon's appointment, and Escanuela.
Spain's disciplinary committee for sports (TAD) last week suspended Escanuela for one month for failing to collaborate in a probe into the federation's finances.
The CSD says it is attempting to track down what happened to at least 700,000 euros ($775,140) the RFET paid out in transactions linked to the Spanish Tennis Foundation and the Spanish Tennis Observatory. - Reuters
