The Clinton Foundation has dropped its self-imposed ban on collecting funds from foreign governments and is winning contributions at an accelerating rate, raising ethical questions as Hillary Clinton ramps up her expected bid for the presidency.

Recent donors include the United Arab Emirates, Saudi Arabia, Oman, Australia, Germany and a Canadian government agency promoting the Keystone XL pipeline.

In 2009, the Clinton Foundation stopped raising money from foreign governments after Mrs. Clinton became secretary of state. Former President Bill Clinton, who ran the foundation while his wife was at the State Department, agreed to the gift ban at the behest of the Obama administration, which worried about a secretary of state’s husband raising millions while she represented U.S. interests abroad.

The ban wasn’t absolute; some foreign government donations were permitted for ongoing programs approved by State Department ethics officials.

The donations come as Mrs. Clinton prepares for an expected run for the Democratic nomination for president, and they raise many of the same ethical quandaries. Since leaving the State Department in early 2013, Mrs. Clinton officially joined the foundation, which changed its name to the Bill, Hillary & Chelsea Clinton Foundation, and has become a prodigious fundraiser as the foundation launched a $250 million endowment campaign, officials said.