GPIO leakage current

I have a DA14580 talking to an MCU via SPI. When the DA goes into extended sleep it powers down the SPI (in arch_turn_peripherals_off()). However for various reasons the MCU must keep the MOSI and SCK lines pulled high during the sleep period. Unfortunately this seems to result in a substantial leakage current flowing into the DA pins, around 140 uA I measure. It should be fairly easy to verify.

This leakage current is way too large for our application (we need the whole system to be under 20 uA during sleep). Is there a way we can prevent it?

Thanks,
Paul.