Oppostion Philippine leader Benigno S. Aquino said today he hopes to return to Manila soon to manage a political campaign against President Ferdinand Marcos and would do it from a jail cell if Marcos permits.

Aquino, who served nearly eight years in prison, said he would return to his country if Marcos grants him freedom of movement during the campaign or at least gives him access to the news media if imprisoned again.

It was not known how the government in Manila would accept Aquino's statement. At times, however, Marcos has hinted at an amnesty for Aquino or even inviting him into the government. No official offers have been made.

Although technically still under a death sentence, Aquino was released from a Philippine prison last May to undergo a heart operation in the United States and has been studying and writing at Harvard University since then.

He flew here last night to meet with another prominent opposition leader, Salvador H. Laurel, who is considered likely to be the joint opposition's candidate for president against Marcos this summer. The campaign period begins next week with the election scheduled for June 16.

Laurel said the United Democratic Organization, an amalgamation of eight anit-Marcos groups, would field a candidate if given a fair chance to campaign but would boycott the election unless certain demands are met. One of them is a longer campaign period than the 55 days allotted by the government.

Aquino, who at 48 is two years too young to be a candidate, has talked several times of returning to Manila.

Pressed to explain how he would manage a campaign from a prison cell, he said he would insist on the right to meet with opposition leaders to discuss programs and to give media interviews during regular prison hours, from 8 a.m. to 5 p.m. each day.

Without some assurances from Marcos, however, Aquino said he would not return.

"If Marcos refused to allow me to campaign freely or to deal with the press from a cell, what's the use of returning?" he asked rhetorically. But if he does return, he said he would risk being held incommunicado once the election is over completed.

Marcos lifted martial law in January but his forces still retain tight control of the government. He has pictured the coming election as one that will give him a new mandate to rule.

The usually fragmented opposition intends to wage a joint campaign this time, and its leaders are to meet April 25 to nominate a candidate. Reports from Manila have described Laurel, once an ally of Marcos, as the most likely opposition candidate.

But Laurel emphasized today that the opposition will boycott the election unless Marcos promises "reasonable" conditions, including a longer campaign period, a purging of electoral rolls, equal time and space in the media and revamping of the election commission.