* President says charges against aide, others "very serious"
* Court due to decide whether to hold detainees in custody
* Charges part of wider graft investigation
* PM's coalition partners considering next steps
Czech President Milos Zeman added to pressure on Saturday on the prime minister to quit over a scandal centred on allegations a close aide abused her powers and bribed politicians.
The government has been in turmoil since prosecutors charged Prime Minister Petr Necas's aide, Jana Nagyova, and seven other people as part of the biggest sweep against political corruption in two decades.
When asked whether he thought the centre-right cabinet led by Necas should stay in office, Zeman, a political opponent of the prime minister, said: "I consider the charges that have been brought to be very serious.
"After hearing from the chief of police and the supreme state attorney, I am coming to the conclusion that they are based on sufficient evidence," he said in his first remarks since a series of police raids on government offices this week.
"This is an indirect but clear answer to your question."
In a defiant speech to lawmakers on Friday, the prime minister dismissed the allegations and said he would stay on. He said he had done nothing dishonest and had no reason not to trust Nagyova.