MOSCOW (Reuters) - Russian Prime Minister Dmitry Medvedev has called for painstaking investigation over detention of Economy Minister Alexei Ulyukayev, Russian news agencies said on Tuesday.

Medvedev discussed Ulyukayev's detention with Russian President Vladimir Putin.

Ulyukayev has been detained over night over a $2 million bribe allegedly received for a "positive" assessment of the deal, which led to Rosneft acquiring a 50 percent stake in Bashneft, the country's Investigative Committee said on Tuesday.

(Reporting by Katya Golubkova; writing by Maria Tsvetkova)