HARARE, Zimbabwe — Zimbabwe's former opposition party said Monday it would boycott the next Cabinet meeting and was considering disengaging from a troubled, four-month-old unity government with President Robert Mugabe.

The Movement for Democratic Change has complained about continued harassment and arrests of Mugabe's opponents and his unilateral appointments of top officials.

Mugabe and Prime Minister Morgan Tsvangirai, bitter rivals, formed their coalition in February, pressed by neighbours to end a decade of violent confrontation and work together to resolve the southern African nation's severe economic crisis.

MDC Vice-President Thokozani Khupe said the latest irritant came Monday, when Mugabe rescheduled the weekly Cabinet meeting from Wednesday to Monday because he was going to be out of town for an African Union summit in Libya. At a news conference, Khupe depicted that as a snub to Tsvangirai, her party's leader, saying he should have chaired the meeting in Mugabe's absence.

Mugabe's party "has not welcomed MDC as an equal partner," said Khupe, a deputy prime minister in the unity government.

Khupe said her party would boycott the rescheduled Cabinet meeting, but remained "committed to the (coalition) agreement in the interest of our people" despite "clear evidence of the absence of a reliable and honest partner."

She did not say when MDC ministers would resume attending Cabinet meetings.

"It is our constitutional right to consider disengagement," she said. "It is time toxicity and insanity are removed (from the coalition)."

The MDC has asked the Southern African Development Community, which pushed for the coalition government to be formed, to intervene. It is asking for help in resolving issues such as Mugabe's appointment of loyalists as the central bank governor and the attorney general, the arrests of and attacks on independent rights activists and MDC lawmakers, and the seizures of white-owned farms.

Khupe said Mugabe loyalists had also frustrated democratic and media reforms.

The Southern African Development Community, though, has said it did not see a reason to step in now.

Tsvangirai was returning Monday from a tour of the West that has focused new attention on tensions in the unity government.

Mugabe is barred by travel restrictions from visiting the countries on Tsvangirai's itinerary, and the leaders with whom the premier had cordial talks -- among them President Barack Obama -- accuse Mugabe of trampling on democracy and ruining a once-vibrant economy.

Zimbabwe's state-run Herald newspaper has reported that some officials aligned to Mugabe were worried about Obama's reference to building a new partnership not with the coalition government, but with Tsvangirai, a former opposition leader who has been beaten and jailed by Mugabe's regime.

Tsvangirai says his three-week trip was aimed at re-engaging with the West, while officials linked to Mugabe have tried to portray it as an attempt to persuade the international community to lift sanctions.

In an interview Friday with The Associated Press, Zimbabwe's Vice-President Joice Mujuru, a Mugabe loyalist, expressed frustration that Tsvangirai's European and U.S. trip didn't raise as much financial aid as her government had hoped.