Provider tells me infected file but NinjaScanner not

Hello,
my provider told me that I have a problem with an infected file. After scanning with NinjaScanner I received a mail that all seems to be OK. When I look into the appropriate folder it looks suspicious to me.
I found in the folder (called ‘docs’) (I cannot remember created this) following files:

• 61e2_50b317ca5c480a7e82451b0d523a93c5.html
• a5fb_6a3ef261b53b4522d6449f27ed0ce6d0.list
• imklj3y.php
• index.php
• sitemap.xml

index.php is empty
Can somebody help me?

Cheers

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