Police have not pressed charges against Anwar since the allegation surfaced last month, raising questions about a case that has stoked political tensions and unsettled foreign investors.
"I always believe that in any criminal investigation, the earlier you wrap up the better it would be," Home (Interior) Minister Syed Hamid Albar, who oversees the police, told Reuters in an interview. "(Otherwise), there will be all sorts of unnecessary rumors."
But he declined to comment on a blogger's posting alleging that a private doctor found no evidence of Anwar's aide being sodomized.
"You cannot have a trial before a trial and a trial in the media and the Internet. I think that is not a very healthy position."
Anwar, 60, has dismissed the claim that he sodomized his former male aide as a political conspiracy to thwart his plans to lead the opposition into power for the first time in Malaysian history.
Sodomy is a crime punishable by up to 20 years imprisonment in Malaysia. The claim mirrors events in 1998, when his political ambitions were halted by a jail term for sodomy and corruption.Syed Hamid strongly dismissed talk of a government conspiracy and said the country's security situation was under control and foreign investors should not be worried.
"I don't buy this conspiracy theory," he said at his office in the nation's administrative capital. "This is just simply a question of justice and fairness."
"To me, if you take off the face and the name, it's another criminal investigation."
Anwar is leading a loose alliance of three opposition parties to try to seize power from Prime Minister Abdullah Ahmad Badawi's government by mid-September.
His attempt to oust the government comes after the ruling National Front coalition, in power since independence from Britain in 1957, suffered its worst electoral setback in a March general election.
The United States and human rights groups have expressed concern over Anwar's case, with Washington insisting that transparency and rule of law must be followed in the case.
New York-based Human Rights Watch has said the allegation against Anwar "lacked credibility."
Syed Hamid, a long-time foreign minister before he was promoted to home minister in March, met foreign diplomats in Kuala Lumpur last week and warned them against meddling in Malaysia's affairs.
In an interview published in the Wall Street Journal on Monday, Anwar said he would continue to speak up despite the government intimidation."There's a lot of intimidation, a lot of efforts to derail this. If I choose to surrender, keep quiet, then it would adversely affect the process."
He called the allegation "unfortunate", but "a sign that the system is crumbling".
(Reporting by Liau Y-Sing and Jalil Hamid; Editing by Bill Tarrant)