The speaker of Poland’s upper house of parliament has called on the government to reveal what it knew about an escalating cash for visas scandal.

Tomasz Grodzki said the issue was ruining the country’s international reputation as a responsible democracy.

The government has released few details but media reports say migrants paid up to $5,000 (£4,000) each to speed up their work visa applications.

Seven people have been charged so far but none are public officials.

The country’s Deputy Foreign Minister Piotr Wawrzyk was sacked last week following the allegations.

His dismissal came the same day that Poland’s Anti-Corruption Bureau (CBA) carried out a search of the foreign ministry. The director of its legal service has also been fired.