It could be days before the executives, many of whom are also civil defense officials, are allowed to go home, said Prime Minister Valery Pustovoitenko.
The civil defense camp is just one part of Pustovoitenko's unorthodox campaign to crack down on tax delinquents, which some newspapers have called heavy-handed and authoritarian.
The business executives gathered at a civil defense base in Pereyaslav-Khmelnytsky, 30 miles outside Kiev, where 30 tents and a makeshift dining hall had been set up.
They were to hear lectures and see films on natural disasters at the base, the Interfax news agency reported. Ukrainian authorities barred foreign journalists from the site, which is surrounded by a concrete fence.
Pustovoitenko said the gathering would last until the executives "solve the question" of their debts.
"I want all those present, all the people of our state, to understand that we shall keep the process of tax and pension fund payments under control," he told the executives Wednesday.
Pustovoitenko egan his tax crackdown last week by bringing executives from debtor companies and organizations to a meeting in Kiev. After Cabinet leaders admonished the executives, Pustovoitenko told them that no one would be allowed to leave the Ukraina Palace until at least some of their debts were paid.
Ukrainian newspapers said the comments touched off general confusion in the hall, with some participants standing in line to sign the required papers while others rushed to find a telephone. Reporters said no one was forcibly prevented from leaving.
Many executives agreed to pay a large portion of their debts within days, and the rest by the end of August.
However, they came up with only $47 million for the pension fund and $31.5 million in taxes, Interfax said.
Also Wednesday, all cabinet staff gave up half of their monthly salaries to the pension fund. Pustovoitenko said he would appeal to all state workers across Ukraine to do the same.