Beyonce Knowles has fuelled rumours her marriage is in crisis.

The 32-year-old singer, who is allegedly leading "separate lives" on tour with her husband Jay Z, sparked new speculation their relationship is on the rocks by changing the lyrics of her 2006 song 'Resentment' while performing their 'On the Run' show in Cincinnati, Ohio on Saturday night (28.06.14).

During the song, which is about a cheating scandal, she altered the track to reflect the current length of her romance with the rapper, singing: "Been ridin' with you for twelve years. Why did I deserve to be treated this way by you? (sic)"

The original lyric should read: "Been ridin' with you for six years. Why did I deserve to be treated this way by you? (sic)"

She also changed the line, "Like I couldn't do it for you like your mistress could" to "Like I couldn't do it for you like that wack b***h could (sic)."

The couple, who have two-year-old daughter Blue Ivy, first started dating in 2002 before secretly tying the knot in New York City in 2008.

Beyonce and Jay's marriage has been under scrutiny since footage emerged of the singer's sister, Solange Knowles, attacking him in an elevator at a Met Ball after party in early May, as the 'Pretty Hurts' hitmaker looked on passively.

The trio later released a statement, insisting they had put the incident, which kicked off after Solange allegedly spotted Jay flirting with fashion designer Rachel Roy in front of her sister, behind them.