Van der Kwast has decided to initiate an inquiry into whether the remuneration could be seen as inappropriate or even corruption.
The inquiry could later form the basis of a criminal investigation.
Carl Bildt said he welcomed the move.
“I think that it’s very good that the situation will be made clear,” he said in an interview with Swedish Radio on Monday morning.
According to the foreign minister, Swedes are not used to seeing options schemes within political life. He accused political opponents, such as the Social Democrats’ Ulrica Messing, of “deliberately casting suspicion” on him.
“The political game is sometimes very dirty,” said Bildt.
He believes that it will take several years before questions about Gazprom become an issue for the Swedish government.
But on Sunday the Green Party reported Carl Bildt to the police’s national anti-corruption unit over the Vostok Nafta affair.
“Now it’s a question of whether it is a gift or actually a bribe,” said the party’s spokesman Peter Eriksson to TV4.
When Bildt was named foreign minister in October he resigned from his board position at Vostok Nafta, whose assets consist almost entirely of shares in the Russian gas giant Gazprom – which in turn wants to build a controversial pipeline under the Baltic Sea. His critics said that his government position could directly influence Gazprom.
Bildt was able to keep his options in Vostok Nafta, but later in the autumn he sold them for 4.8 million kronor. He said that under the company’s rules he could not give up the shares, but media reports suggested the opposite – that Bildt in fact should not have had a right to the options since he resigned voluntarily and the board later decided that he should be able to keep them.
Bildt has emphasised that he followed the regulations and said that during his four years on the board Vostok Nafta’s shares had progressed well – which was also advantageous for Swedish interests such as the AP funds.
Prime minister Fredrik Reinfeldt backed his foreign minister in an interview on TV4 on Monday morning.
“I think he has dealt with these committments in the way he said he would,” said Reinfeldt.