A Turnbull government MP took a publicly funded "study tour" to Europe that included a visit to a Polish coal mine in which he owns shares.

Luke Simpkins, a West Australian Liberal, slugged taxpayers nearly $5000 for his seven-day jaunt through Poland and the Netherlands in April and May last year.

In his written report to the Department of Finance, Mr Simpkins said the purpose of his journey to Poland was to "examine the bilateral relationship, including economic opportunities for Australian businesses".

But he did not disclose that he had a direct financial interest in the one Polish coal mine he chose to visit - the Australian-owned Prairie Mining project in Lublin, two hours' drive south-east of Warsaw.