The hugely popular free instant messaging system WhatsApp Messenger is at number one again in the paid for iPhone app chart this week.

The app allows cross-platform mobile messaging so people can exchange messages without having to pay for an SMS.

Cryptic puzzle app The Room, by Fireproof Games, tops the paid for iPad chart, while YouTube sits at number one in the iPhone free top ten.

Meanwhile, Draw a Stickman: Epic HD Free from was the most popular free iPad app this week. The game allows users to guide a stickman through a series of adventures to solve puzzles.

Another popular game forcing its way into two Apple charts this week is Bad Piggies which features at number two in the iPhone paid top ten and Bad Piggies HD which features at number three in the iPad paid chart.

This week ITV player has proved more popular than the BBC iPlayer by just one spot in the iPad free chart.

The Apple Official UK App Store Weekly Charts in full:

iPhone (Paid):

1.) Whats App Messenger - WhatsApp Inc.

2.) Bad Piggies - Rovio Entertainment Ltd

3.) Grand Theft Auto 3 - Rockstar Games

4.) Need for Speed: Most Wanted - Electronic Arts

5.) Plague Inc. - Ndemic Creations

6.) Bike Baron - MountainSheep

7.) Sleep Cycle Alarm Clock - Maciek Drejak Labs

8.) Fruit Ninja - Halfbrick Studios

9.) Angry Birds Space - Rovio Entertainment Ltd

10.) Where's Wally? In Hollywood - Ludia

iPhone (Free):

1.) YouTube - Google, Inc.

2.) Don't Forget The Lyrics - KOALA DE DEVELOPMENT SC

3.) TextPics - FTW Innovations

4.) iPlayer Radio - Media Applications Technologies Limited

5.) Angry Gran Run -

6.) Stacheify - Apptly LLC

7.) Flashlight - iHandy Inc

8.) Podcasts - Apple

9.) Summly - Summlu Limited

10.) HotUKDeals - HotUKDeals

iPad (Paid):

1.) The Room - Fireproof Games

2.) Need For Speed: Most Wanted - Electronic Arts

3.) Bad Piggies HD - Rovio Entertainment Ltd

4.) Plants vs. Zombies HD - PopCap

5.) Pages - Apple

6.) TETRIS for iPad - Electronic Arts

7.) Peppa Pig Theme Park - P2 Games Limited

8.) Garageband - Apple

9.) FIFA 13 by EA SPORTS - Electronic Arts

10.) Toca Tailor - Toca Boca AB

iPad (Free):

1.) Draw a Stickman: Epic HD Free -, Inc

2.) Angry Gran Run -

3.) Contract Killer 2 - GLu Games Inc

4.) BBC Good Food - Recipes, tools & cooking tips - BBC Worldwide

5.) Skype for iPad - Skype Communications S.a.r.l

6.) ITV Player - ITV

7.) BBC iPlayer - Media Applications Technologies Limited

8.) eBay for iPad - eBay Inc

9.) Podcasts - Apple

10.) Spider: The Secret of Bryce Manor HD - Tiger Style