Geneva  - The jet dispatched earlier this week by the Swiss government to collect two of its citizens detained in Libya for over a year, left early Friday without the men, as the saga refused to reach a conclusion.

In a short and terse statement, the Swiss Federal Department of Finance said the "preparations for their return are continuing," but added no details.

"The plane is required elsewhere," the statement read. The jet had landed in Tripoli on Tuesday, with the apparent intention of bringing the two Swiss home.

The men, one of whom works for the industrial engineering group ABB, have not been allowed to leave Libya since last July, when they were arrested just days after Geneva's police force detained the son and daughter-in-law of Libyan leader Colonel Muammar Gaddafi.

The Libyan couple were accused of physically abusing their domestic servants at a lakeside hotel. After two days in detention, they were released.

Libya, demanding an apology, retaliated against Switzerland by detaining the Swiss nationals, gradually reducing trade and business flows to a trickle and lowering diplomatic relations.

Last week, Swiss President Hans Rudolph Merz - who is also the finance minister- traveled to North Africa to sign a deal with Libya meant to restore normal relations. He said the Geneva arrest was unjust and apologized, drawing the ire of many in the canton.

Merz then left the country without the two, sparking another round of criticism, but with an agreement to reset trade and diplomatic ties between Bern and Tripoli.

The president pledged the two Swiss citizens would be returned home before the beginning of September and said he had assurances from the Libyan government.

Observers have said that despite the apparent attempt by the Swiss to get the men home this week, they might not be released until September 1, when Gaddafi will mark 40 years since his rise to authoritarian power in a bloodless coup.

Jean Ziegler, a former member of the Swiss parliament and a political thinker, called the affair "botched diplomacy" and an "an unparalleled scandal" in an interview with the German Press Agency dpa.

The saga with Libya has touched on multiple hot buttons, including Switzerland's diplomatic sway, its business sector, the nature of the country's overarching devolved federalist power structure and the way the collective government reaches decisions. (dpa)