The United States says it is withholding judgment on the Zimbabwe unity government that was sworn into office on Wednesday until it sees evidence of true power-sharing and good governance.  In the meantime, U.S. sanctions against President Robert Mugabe and key his associates will remain in place. 

The State Department has congratulated Morgan Tsvangirai, the former Zimbabwe opposition leader, on his swearing-in as the country's new prime minister.

But the Obama administration is maintaining a cautious approach, with officials saying it remains to be seen whether long-time Zimbabwe President Robert Mugabe, who remains head of state, is willing to  share real power with his political rival.

The United States and European Union countries have in recent years imposed travel and financial sanctions against Mr. Mugabe, his family members and close associates because of electoral and human rights abuses by the Mugabe government.

U.S. humanitarian aid, to help deal with Zimbabwe's cholera outbreak, among other things, has continued.  But at a news briefing Wednesday, State Department Acting Spokesman Robert Wood said curbs on other aid will remain until it can be determined whether the power-sharing arrangement actually works.

"We certainly congratulate Morgan Tsvangirai on assuming the position of prime minister," he said. "However, we will reserve our judgment on the new government until we see what types of actions it takes.  We will not consider providing additional development assistance, or even easing sanctions, until we see effective governance in the country and that is going to be key."

Wood acknowledged that Zimbabwe needs help in rebuilding its shattered economy, but he said the United States, before changing its approach, needs to see evidence of good governance and particularly "real, true power-sharing" on the part of Mr. Mugabe.

Zimbabwe is suffering from food shortages, runaway inflation and soaring unemployment, which the United States has largely blamed on misrule by the long-time president.

Mr. Tsvangerai's Movement for Democratic Change won parliamentary elections nearly a year ago, breaking a decades-long hold on power by Mr. Mugabe's ZANU-PF party.  But power-sharing negotiations that began last September stalled over the distribution of cabinet posts.

The Bush administration, frustrated by the lack of progress in those talks, dropped its support for the process and joined in calls that Mr. Mugabe step down.

When it took office last month, the new U.S. administration launched a policy review and softened its approach to give African mediation on Zimbabwe power-sharing more time to work, though U.S. diplomats remain skeptical about Mr. Mugabe's intentions.