Maseko, who completed his testimony on Thursday, told the Commission of Inquiry into State Capture headed by Deputy Chief Justice Raymond Zondo that the Guptas operated a parallel system of government.
He said the Guptas would pull out big guns and drop former president Jacob Zuma's name to get their way with senior government officials and cabinet ministers.
According to Maseko, the Guptas used to summon government officials, including him, to their sprawling Saxonwold compound in Joburg and reprimand them if they refused to follow their instructions.
Maseko's successor as head of the Government Communication and Information System (GCIS), Phumla Williams, was scheduled to begin her testimony today.
Williams has been acting GCIS chief executive and government spokesperson for a number of years.
She was expected to shed light on the family's newspaper The New Age and 24-hour television news channel ANN7, and how much advertising they received from government departments' communications budgets that were spent through the GCIS.
Earlier this week, Maseko testified that he and several former directors-general, including Barry Gilder, Xoliswa Sibeko and Thozi Gwanya, were concerned about state capture and wanted to take a stand against it.
Maseko said the former directors-general were worried about the capture of the state by the Guptas.
Justice Zondo asked the commission's legal and investigations teams to ensure serious efforts were made to contact the former directors-general who, along with Maseko, publicly expressed their concerns about state capture.
“The country needs them,” Justice Zondo said.
Maseko told the commission that there were many senior public servants and middle managers who have information on the Guptas' capture of the state and their political principals' irregular instructions.
“Very few people are willing to come forward,” Maseko said, adding that Justice Zondo was also having trouble getting witnesses to testify before the commission.
The former public works director-general also told Justice Zondo about Ajay Gupta's approach when the controversial family wanted the GCIS to support the establishment of a newspaper and a TV news channel.
According to Maseko, Ajay demanded a share of the GCIS's R600 million media buying budget between September and October 2010.
Maseko was the fourth witness to testify before the commission following Treasury's acting chief procurement officer Willie Mathebula, former ANC MP Vytjie Mentor and former deputy finance minister Mcebisi Jonas.
The Guptas and some other implicated parties, including Zuma’s former aide Lakela Kaunda, the Hawks' Major-General Zinhle Mnonopi and advocate Mandla Mtolo, have asked to be allowed to cross-examine witnesses appearing before the commission.