chief Lalu Prasad on Sunday asked Prime Minister Narendra Modi to check the rising prices of onions and arrest those hoarding the vegetable."The central government has failed to raid and catch onion black-marketeers and take action against onion hoarders," the former Bihar chief minister tweeted."The central government should act fast to deliver cheap onion to people. It is possible only if the government checks and controls onion prices," he added.Criticizing the central government for failing to bring back black money as promised during parliamentary polls, Lalu Prasad said: "When the NDA government is not able to catch onion black-marketeers in the country, how can it bring black money from foreign land?"Lalu Prasad's remarks came as onion prices crossed the Rs.80 per kg mark at many places in Bihar on Sunday.