Swaziland, which has the world's highest rate of HIV infection, has cancelled events to mark World Aids Day, shocking activists.
The government says it is working hard to fight Aids
A royal decree was issued just a day before the prime minister was due to give a speech, saying it would clash with a traditional ceremony.
Some 38% of Swazi adults are HIV positive, rising to 56% for women in their late twenties.
King Mswati, who has 13 wives, is criticised for setting a bad example.
The speech was cancelled because the month-long Incwala harvest festival has started and all other ceremonies are banned during this period.
Sex-ban ends early
Prime Minister Themba Dlamini is expected to attend the Incwala ceremony.
Earlier, Mr Dlamini told the BBC's Newshour programme that the government was working hard to reduce the rate of HIV infection, with campaigns across the country.
"It has taken time for Africa to believe that Aids is a killer," he said.
King Mswati is criticised for having so many wives
The BBC's Thulani Mthethwa in the capital, Mbabane, says Aids activists see the cancellation as a sign that government officials put loyalty to King Mswati ahead of a national disaster.
Despite the ban, some activists have organised a dinner to commemorate World Aids Day.
People living with HIV are also upset that there is a shortage of free anti-retroviral drugs.
Some $1.5m-worth of funding was cancelled because the government does not have effective systems to monitor patients taking ARVs.
In August, King Mswati ended a four-year sex ban on young Swazis imposed to curb the spread of HIV/Aids.
Our correspondent says this was very unpopular, especially in urban areas.