A court in Malawi has adjourned the corruption case of Vice-President Cassim Chilumpha, until a judicial review of his arrest is conducted.
Mr Chilumpha has fallen out with President Mutharika (pictured)
Police questioned him at home for two hours on Tuesday, his spokesman said.
The allegations relate to contracts allegedly awarded to companies that supported the government while Mr Chilumpha was a minister six years ago.
The summons comes amid a power struggle between Malawi's President Bingu wa Mutharika and his predecessor.
Mr Chilumpha is an ally of former leader Bakili Muluzi, whose United Democratic Front (UDF) party is trying to impeach the president.
Mr Mutharika was elected president while a member of the UDF, but has since split from the party, and targeted some former leaders in an anti-corruption drive.
Mr Chilumpha, a UDF member and ally of Mr Muluzi, had criticised the arrests of two MPs involved in the impeachment effort, and was reported not to be attending cabinet meetings any more.
"The vice president has been issued with a summons to appear before the chief resident magistrate in Lilongwe [the capital] on Wednesday," Horace Nyaka, the vice president's spokesman, said.
Mr Chilumpha has been investigated before over allegations that as education minister in Mr Muluzi's government he awarded contracts worth US$2m to party supporters, who in turn gave contributions to the president's election campaign.
However the investigation was dropped, and the UDF said it had only been revived for political reasons.
"It is not surprising that government had decided to arrest the vice president, because he is UDF," said UDF spokesman Sam Mpasu.
"This is yet another fabrication of lies against top party members."
Mr Chilumpha's lawyer would not comment on the summons.
The political crisis has paralysed government, angering foreign donors at a time when food shortages are threatening five million people.