Khloe Kardashian is ''jealous'' of Kylie Jenner's lips.

The reality TV star, 30, is said to be envious of her 17-year-old sister's plump pout and has been trying to emulate her look.

While Kylie recently confessed to having lip fillers to increase the size of her lips, Khloe is also said to have tried out the same ''temporary'' procedure.

A source told Hollywoodlife.com: ''It does make her a little jealous. Khloe has been getting fillers in her face and in her lips for a while. She just does the bare minimum because she doesn't want to look like she's had anything done.

''The last time she went, she got a little extra filler in her lips, way more than she normally does, and that's totally because of Kylie! She sees how great Kylie looks and how much attention she's getting from guys, and she wants that, too.''

Meanwhile, the 'Keeping Up with the Kardashians' star has openly supported her younger sibling's decision and previously urged her to come clean about undergoing the treatment.

Speaking on an episode of the E! series, she said: ''Kylie decided to plump her lips and I don't think there is anything wrong with that. I think if you've done something though, it is right to cop up to it. If you avoid the question you're gonna look like a liar.''

Kylie previously urged her fans not to copy her look after the #KylieJennerChallenge started trending on Twitter, prompting users to go to extreme lengths to mimic her full lips.

After photographs of fans with severely swollen mouths began to flood the site, she tweeted: ''I'm not here to try & encourage people/young girls to look like me or to think this is the way they should look.

''I want to encourage people/young girls like me to be YOURSELF & not be afraid to experiment w your look.''