Sitemap Error: “Warning: set_time_limit():…”

Hi.

I keep seeing the following error (plus other errors which I think are related) in admin when doing various actions like updating post, activating plugins, etc.

” Warning: set_time_limit(): Cannot set max execution time limit due to system policy in /customers/9/5/4/you************by.co.uk/httpd.www/wp-content/plugins/smartcrawl-seo/includes/tools/sitemaps.php on line 282 ”

Any suggestions on how to fix?