Kaspars, If about my version, that is just fast-typing typo :) (thanks for cleaning) My mistake! Of course need to escape dots

OK, by cleaning-up made small “upgrade” too:
for both .html and .php :)
RewriteCond %{THE_REQUEST} \/index\.(php|html)\ HTTP [NC]
RewriteRule (.*)index\.(php|html)$ /$1 [R=301,L]