Unions at Spanish news agency EFE accused the state-owned outlet's head of news on Monday of censoring information about last week's bombings in Madrid to help the Government.
EFE's chief spokeswoman, Ana Vaca de Osma, denied the charge, telling Reuters the accusations made by the unions in their statement were false.
The unions said Miguel Platon had created a “regime of censorship and manipulation” in which EFE withheld information about a possible Islamist role in the attacks to help push the Government line that Basque separatists were to blame.
“It is totally false that EFE had privileged information in connection with the March 11 attacks and that it withheld information about the attacks,” the agency said in a statement.
The accusations against Mr Platon came a day after a general election in which one of the hot issues was the Government's handling of information on the rush-hour train bombings that killed 200 people last Thursday.
Ministers were quick to blame Basque guerrilla group ETA for the attacks, but evidence has since built up suggesting Osama bin Laden's Al Qaeda network was responsible.
Many Spaniards felt the centre-right Government pointed the finger at ETA because it stood to gain politically if the Basque group had been guilty.
That perception contributed to the ruling party's shock electoral defeat on Sunday.
The Government is known for its hard line against ETA, whereas its support for the war in Iraq was deeply unpopular.