importing xml error

Hi,
i tryed to import an xml-file from ww.wp.xz.cn at my local provider, Host Europe.

I always got this message:

“Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 37796 bytes) in /is/htdocs/****/wp-includes/media.php on line 258”

The xml-file is 5 MB.

I splitt it into 12 parts. First 4 parts work, part 5 i get the same error.

Some ideas whats going wrong here? And what i can do?

Thx, Frank