ISLAMABAD (AP) — Pakistan's anti-corruption body arrested a prominent opposition leader on Monday who has been a vocal critic of the prime minister.

Ahsan Iqbal was arrested hours after he publicly described Prime Minister Imran Khan as the country's “biggest beggar.” He said Khan has failed to improve Pakistan's ailing economy despite getting billions of dollars in new loans from the IMF and other countries.

Ahsan Iqbal served as interior minister in the government of former Prime Minister Nawaz Sharif, who was himself removed from office in 2017 over corruption allegations, and sentenced to prison the following year.

Iqbal was arrested Monday after he appeared before the National Accountability Bureau. He was being questioned about alleged corruption in the construction of a sports stadium several years ago in his constituency in the eastern Punjab province.

Maryam Aurangzeb, a spokeswoman for Iqbal's political party, called his arrest “political victimization” and said he was detained “because he refused to stop criticizing Imran Khan.” She said the party will continue to push for Khan's resignation.

Iqbal's arrest was yet another addition to the long list of politicians from opposition parties who have been arrested on corruption charges since Khan took office. He campaigned in last year's election on promises to stamp out governmental corruption.

Khan's predecessor, Sharif, got a seven-year prison sentence in 2018 for corruption and money laundering. However, his health has recently deteriorated, and he's currently receiving medical treatment in London after being released on bail earlier this month.

In June, Khan's government arrested former President Asif Ali Zardari in connection with a money laundering case. But a court freed him earlier this month on bail, also on medical grounds.

Sharif and Zardari are longtime political rivals but their parties have vowed to oust Khan's government, citing increasing inflation and a spike in the price of essential foods.